MEASURING DEVICE

Abstract

A coordinate measuring machine (1) (measuring device) comprises: a probe (10) (measurement performing unit) that performs a measurement operation on a measurement target; an electrical section (122) arranged in a part of the probe (10); a temperature sensor (124) that is provided for the electrical section (122) and outputs a detection signal based on a temperature obtained by measurement; and a controller (20) (measurement calculator) that calculates a measurement result of the measurement target, wherein the controller (20) calculates the measurement result by compensating a measurement value obtained by the measurement operation based on a processed signal obtained by applying a low-pass filter to the detection signal output from the temperature sensor (124).

Description

TECHNICAL FIELD

[0001] The present invention relates to a measuring device. STATE OF THE ART

[0002] When a measuring device measures coordinates on a surface of a measurement target, it is necessary to consider a dimensional change in the measuring device due to a temperature change, that is, a dimensional change caused by stretching of the measuring device due to thermal expansion. For example, Document 1 (JP 2005-181293 A) describes a measuring device (coordinate measuring machine) in which a probe may include a temperature sensor that measures a temperature of the probe, and temperature compensation of measurement data may be further performed based on a temperature difference between a measured temperature of the probe and a reference temperature (typically 20 degrees C).

[0003] The measuring device, as described above, performs a compensation process based on the temperature obtained by measuring the temperature of the probe. Here, the probe may include a pin, a support supporting the pin, a mechanism section disposed in the support and configuring a movement mechanism of the pin, a sensor, and an electrical section. In this case, when an electrical component provided for the electrical section is supplied with power, the electrical component becomes a heat source.

[0004] However, in the probe, the heat dissipation takes longer with increasing distance from the electrical section, including the electrical component as the heat source, making the temperature increase slow over time. Furthermore, the heat dissipation becomes more rapid with increasing distance from the electrical section, resulting in a decrease in the saturation temperature. Therefore, the strain of the entire probe calculated from a temperature sensor reading does not directly match the actual strain of the entire probe when the temperature sensor is designed for the electrical section, which is the heat source.Thus, when compensation is performed based on the temperature measured by the temperature sensor, for example, immediately after turning on the power source of the measuring device, it is not possible to perform an appropriate compensation operation corresponding to the strain of the entire probe, and a user must wait until the temperature increase reaches saturation.

[0005] The measuring device may include temperature sensors for respective parts of the probe, and the temperature sensors may measure the temperatures of the respective parts of the probe. However, in this case, a space for the temperature sensors is required to prevent the temperature sensors from interfering with the measurement target and other components of the measuring device. Furthermore, providing multiple temperature sensors increases the device cost, and the wiring becomes complex due to the wiring lines drawn from the respective temperature sensors to the electrical section.

[0006] It should be noted that the above problems can be applied not only to the measuring device provided with the probe as described in Document 1, but also to any other measuring device in which a temperature sensor for an electrical section is provided, which is arranged in a measurement performing unit that performs a measurement. For example, in a length measuring machine that measures a length of a measurement target, the length of the measurement target is measured by moving a detection head, which is the electrical section, on a scale along a longitudinal direction. Such a length measuring machine can perform a compensation operation corresponding to a dimensional change due to a temperature change in the scale. Here, the temperature sensor for the electrical section (e.g., the detection head) may be provided, which is arranged slightly separately from the scale as the temperature measurement target.In this case, as with the probe, it takes time for the heat from the electrical section to propagate to the scale, which can lead to a gap between the expansion of the entire scale calculated from a temperature sensor reading and the actual expansion of the entire scale. This makes it impossible to perform the appropriate temperature compensation process until the temperature increase in the electrical section and the scale reaches saturation. SUMMARY OF THE INVENTION

[0007] An object of the invention is to provide a measuring device capable of performing an appropriate compensation operation corresponding to an actual temperature in a measurement performing unit.

[0008] A measuring device according to a first aspect of the present disclosure includes: a measurement performing unit configured to perform a measurement operation on a measurement target; an electrical section disposed in a part of the measurement performing unit; a temperature sensor provided for the electrical section and configured to output a detection signal based on a temperature obtained by measurement; and a measurement calculator configured to calculate a measurement result of the measurement target, wherein the measurement calculator is configured to calculate the measurement result by compensating a measurement value obtained by the measurement operation based on a processed signal obtained by applying a low-pass filter to the detection signal output from the temperature sensor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically illustrates an exemplary measuring device according to a first embodiment. Fig. 2 illustrates temperature changes in respective parts of a probe according to the first embodiment. Fig. Figure 3 illustrates an example of stretching of the entire probe due to a temperature increase. Fig. 4 illustrates an exemplary relationship between a temperature measured by a temperature sensor and a temperature based on a processed signal after a low-pass filtering operation in the first embodiment. Fig. Figure 5 illustrates exemplary variations of coordinates of measurement results with respect to elapsed time. Fig. 6 schematically illustrates an exemplary measuring device according to a second embodiment. Fig. Figure 7A illustrates an example low-pass filter circuit. Fig. Figure 7B illustrates another example low-pass filter circuit. Fig. Figure 7C illustrates another example low-pass filter circuit. Fig. Figure 7D illustrates another example low-pass filter circuit. Fig. 8 schematically illustrates an exemplary measuring device according to a third embodiment. Fig. 9 schematically illustrates an exemplary measuring device according to a fourth embodiment. DETAILED DESCRIPTIONFirst embodiment

[0009] A measuring device according to a first embodiment of the present disclosure will be described below.

[0010] Fig. 1 schematically illustrates a coordinate measuring machine which is an exemplary measuring device of the first embodiment.

[0011] In Fig. 1, a coordinate measuring machine 1 includes a probe 10, a controller 20, a personal computer (PC) 40, and the like. Furthermore, the coordinate measuring machine 1 includes a table (not shown) on which a measurement target is placed, and a probe moving mechanism 30 that moves the probe 10 in an X direction, a Y direction orthogonal to the X direction, and a Z direction orthogonal to the X and Y directions. The probe moving mechanism 30 includes an X scale 31 that measures a movement amount in the X direction, a Y scale 32 that measures a movement amount in the Y direction, and a Z scale 33 that measures a movement amount in the Z direction.

[0012] The probe 10 corresponds to a measurement performing unit of the present disclosure. The probe 10 includes a pin 11 and a support 12 that supports the pin 11.

[0013] The stylus 11 includes a shaft 111 and a tip ball 112 provided at the tip of the shaft 111. When the coordinate measuring machine 1 measures a shape of a measurement target, the controller 20 controls the probe moving mechanism 30 to cause the probe 10 to move in a three-dimensional space, so that the tip ball 112 of the stylus 11 moves along a surface of the measurement target.

[0014] The support 12 supports a base end of the pin 11 (an end opposite the tip ball 112 of the shaft 111) so that the pin 11 is movable. The support 12 is, for example, a cylindrical member with a predetermined diameter. A mechanism section 121 and an electrical section 122 are provided in the support 12.

[0015] The mechanism section 121 supports the pin 11 so that the pin 11 is movable. Specifically, the mechanism section 121 supports the pin 11 so that the pin 11 is movable within a predetermined range in an axial direction of the pin 11 (Zp direction), an Xp direction orthogonal to the Zp direction, and a Yp direction orthogonal to the Xp and Zp directions. Furthermore, the mechanism section 121 includes a probe sensor (not shown) that measures the movement amounts of the pin 11 in the Zp, Xp, and Yp directions as probe coordinates.

[0016] The electrical section 122 is an electrical board on which a temperature sensor 124 and any electrical components 123 other than the temperature sensor 124 are mounted. For example, the probe coordinates are detected by the probe sensor, and the temperature is measured by the temperature sensor 124.

[0017] The temperature sensor 124 is built into the support 12 of the probe 10 and is directly provided for the electrical section 122, which is the electrical board.

[0018] The temperature sensor 124 measures a temperature of the probe 10, which is the measurement performing unit of the present disclosure.

[0019] Here, a temperature increase in probe 10 is described. Fig. 2 illustrates temperature changes in respective parts of the probe 10. Fig. 3 illustrates an example of stretching of the entire probe 10 due to a temperature increase.

[0020] In the probe 10 of the first embodiment, when the electrical component 123 provided for the electrical section 122 is supplied with power, the electrical component 123 becomes a heat source, thereby causing a temperature increase. Since the temperature sensor 124 is provided together with the electrical component 123 for the electrical section 122, a temperature measured by the temperature sensor 124 is substantially the same as that of the electrical component 123, along with the temperature increase in the electrical component 123, which has a large temperature change as shown by a line A in Fig. 2 is displayed.

[0021] In Fig. 2, a temperature increase at a position in the mechanism section 121 near the electrical section 122 is indicated by a line B, a temperature increase at a position in the mechanism section 121 near the pin 11 is indicated by a line C, and a temperature increase in the pin 11 is indicated by a line D. As shown by the lines A to D of Fig. 2, the heat generated in the electrical component 123 is transferred to respective parts of the probe 10, so that the heat propagation is delayed with increasing distance from the electrical section 122 and the saturation temperature decreases with increasing distance from the electrical section 122. Thus, the rate of temperature increase and the degree of temperature increase differ in the respective parts of the probe 10. As a result, as shown in Fig. 3, the expansion of the entire probe 10 exhibits a slower change than the temperature measured by the temperature sensor 124.

[0022] For the above reason, if a dimensional change of the probe 10 due to the temperature change is compensated as it is using the temperature measured by the temperature sensor 124, the value for this compensation is not consistent with that based on an actual dimensional change of the probe 10. Thus, in the first embodiment, a low-pass filter process is applied to the temperature measured by the temperature sensor 124 to calculate a compensation value corresponding to the actual dimensional change of the probe 10. The compensation using a low-pass filter will be described later.

[0023] The controller 20 corresponds to a measuring computer of the present disclosure. The controller 20 controls the entirety of the coordinate measuring machine 1 to perform a measurement on a measurement target using the probe 10 and output a coordinate measurement result. The measuring computer of the present disclosure can be configured by the controller 20 and the personal computer (PC) 40 described later. For example, the controller 20 is configured to include at least a memory 21 and a processor 22. The memory 21 stores a variety of programs and a variety of data. The processor 22 achieves a variety of functions by reading and executing the programs recorded in the memory 21.

[0024] Specifically, the processor 22 functions as a measurement control section 221, a measurement coordinate acquisition section 222, a probe coordinate acquisition section 223, a temperature acquisition section 224, a filter application section 225, and a probe coordinate compensation section 226 by reading and executing the plurality of programs.

[0025] The measurement control section 221 controls the probe moving mechanism 30 to move the probe 10 relative to the measurement target. For example, the measurement control section 221 refers to design data for the measurement target, measurement coordinates measured by the measurement coordinate acquisition section 222, and the like, and moves the probe 10 along a predetermined location. Alternatively, the measurement control section 221 may refer to probe coordinates measured by the probe coordinate acquisition section 223 and control the probe moving mechanism 30 to make the pressing amount of the probe constant.

[0026] The measurement coordinate detecting section 222 detects measurement coordinates (X, Y, Z) of the probe 10, that is, the amounts of movement in the XYZ directions of the probe 10 measured by the X scale 31, the Y scale 32, and the Z scale 33.

[0027] The probe coordinate detecting section 223 detects probe coordinates (Xp, Yp, Zp) measured by the probe sensor provided for the probe 10.

[0028] The temperature detecting section 224 detects a detection signal corresponding to a measurement temperature output from the temperature sensor 124.

[0029] The filter applying section 225 applies the low-pass filtering process to the detection signal acquired by the temperature detecting section 224 and outputs a signal after the low-pass filtering process as a processed signal. That is, in the first embodiment, the processor 22 functions as the filter applying section 225 by reading and executing a filter program recorded in the memory 21. The filter applying section 225 generates the processed signal from the detection signal through an arithmetic operation based on the filter program.

[0030] For example, a low-pass filter of formula (1) is used, in which the detection signal output from the temperature sensor 124 is denoted by R, the processed signal is denoted by Y, a time constant of the low-pass filter is denoted by τ, and a Laplace operator is denoted by s. Y(s)=11+τsR(s)

[0031] Since the temperature measured by the temperature sensor 124 is T S is denoted by , the temperature after the low-pass filtering process (temperature used for a compensation process described later) with T L and a sampling period of the detection signal output from the temperature sensor 124 is denoted by Δt, the formula (2) is obtained from the formula (1). TL[n]=aTL[n−1]+(1−a)TS[n]where a=τ / (Δt+τ)

[0032] In formula (2), n represents the n-th sample, T L [n] represents a temperature T L after the n-th low-pass filter process, T L [n-1] represents a temperature T L after the (n-1)-th low-pass filter process and T S [n] represents a temperature T S obtained by the n-th measurement using the temperature sensor 124.

[0033] Fig. 4 illustrates an exemplary relationship between the temperature T measured by the temperature sensor 124 S and the temperature T L based on the processed signal after the low-pass filtering process. Fig. 4 illustrates a relationship of temperatures T S , T L at the time elapsed after the power source of the coordinate measuring machine 1 was switched from OFF to ON, the temperature T S is represented by a solid line and the temperature T L is represented by a dashed line.

[0034] By turning on the power source of the coordinate measuring machine 1, the electrical component 123 of the electrical section 122 is supplied with power, thereby making the electrical component 123 a heat source to increase the temperature. The temperature sensor 124 is provided directly for the electrical section 122. Thus, when the electrical component 123 of the electrical section 122 is supplied with power, the temperature T increases. S strong and then stabilizes at a predetermined temperature, as in the Fig. 2 and Fig. 4 illustrated.

[0035] In contrast, the temperature T L calculated after the low-pass filtering process as shown by formula (2), and the temperature T L increases more slowly than the temperature Ts and stabilizes at a predetermined temperature, as in Fig. 4 illustrated.

[0036] As can be seen from the comparison between Fig. 3 and Fig. 4, the dashed line representing the temperature T L after the low-pass filtering process in Fig. 4, in the form near the solid line, which represents the elongation of the entire probe 10 in Fig. 3, and the dimensional change of the probe 10 due to the temperature increase can be compensated by performing the compensation process based on the temperature T L be appropriately compensated after the low-pass filtering process.

[0037] The probe coordinate compensating section 226 outputs compensated probe coordinates obtained by compensating the probe coordinates based on the temperature T Lcorresponding to the processed signal calculated by the filter applying section 225. In the first embodiment, an example is given in which the probe coordinate compensating section 226 sets the probe coordinates measured by the probe sensor as a measured value and compensates the measured probe coordinates to provide probe coordinates as a measurement result. However, the present disclosure is not limited to this. For example, the measurement result may be provided by setting, as the measured value, a value obtained by adding the probe coordinates measured by the probe sensor to the measurement coordinates measured by the measurement coordinate acquiring section 222 and adding the compensation value to this value.

[0038] Fig. Figure 5 illustrates exemplary variations of measurement results. In Fig. 5, a dotted line represents a variation of coordinates of a measurement result after the compensation process based on the temperature T L a dashed line represents a variation of coordinates of a measurement result after the compensation process based on the temperature T S and a solid line represents a variation of coordinates of a measurement result before the compensation process (without the compensation process).

[0039] In the Fig. 5, when the power source of the coordinate measuring machine 1 is switched from OFF to ON, the temperature of each part of the probe 10 changes, with the electrical section 122 serving as a heat source and extending the entire probe 10. Here, heat is slowly transferred to each part of the probe 10 compared to the temperature T measured by the temperature sensor 124. S, as described above. Thus, the actual elongation of the entire probe 10 changes gradually and the measurement result also changes gradually, as shown by the solid line in Fig. 5. As can be seen from the comparison with Fig. 4, the solid line showing the change in the measurement result in Fig. 5, essentially the same shape as the dashed line representing the change in temperature T L after the low-pass filtering process in Fig. 4 represents.

[0040] The probe coordinate compensating section 226 compensates the measured value to cancel such a dimensional change of the probe 10 due to the temperature change, and outputs the compensated value as the measurement result.

[0041] For example, in a case where the measurement result is based on the value indicated by the dashed line in Fig. 5 displayed temperature T Scompensated, the compensation amount is too large immediately after the power source is switched from OFF to ON, resulting in a large change in the measurement result. In this case, a certain period of time is required to saturate the temperature increase in each part of the probe 10 and stabilize the strain of the entire probe 10 at a constant value. Although the appropriately compensated measurement result is obtained after the certain period of time, it takes time to obtain the appropriate measurement result.

[0042] On the contrary, the measurement result is obtained by compensating the measured value based on the temperature T L which corresponds to the processed signal after the low-pass filtering process in the first embodiment. This makes it possible to perform the compensation corresponding to the actual strain of the probe 10, as shown by the dot-dash line in Fig. 5 and calculate the appropriate measurement result while greatly reducing or eliminating the waiting time.

[0043] In the above, although the description has been made about the compensation in the axial direction (Zp direction) of the probe 10 which is large in an extension / contraction amount due to the temperature change, similar compensation can be performed in the Xp direction and the Yp direction. Shape calculation by PC

[0044] The PC 40 is communicatively connected to the coordinate measuring machine 1. The PC 40 calculates surface coordinates or a surface shape of the measurement target based on the compensated probe coordinates compensated by the probe coordinate compensation section 226 and the measurement coordinates measured by the X-scale 31, Y-scale 32, and Z-scale 33. For example, when a profile movement of the probe 10 is performed along a surface of the measurement target, the coordinates of a location of contact positions with the tip ball 112 of the probe 10 are calculated based on the compensated probe coordinates and the measurement coordinates, respectively. Functions and effects of the first embodiment

[0045] The coordinate measuring machine 1 of the first embodiment includes the stylus 11 that performs a measurement operation on a measurement target, the probe 10 including the support 12 that supports the stylus 11, and the controller 20. The support 12 of the probe 10 is provided with the electrical section 122 and the temperature sensor 124. The electrical section 122 includes the electrical component 123 that controls the probe 10. The temperature sensor 124 is provided for the electrical section 122 and outputs a detection signal based on a temperature obtained by measuring a temperature of the probe 10. The controller 20 calculates a measurement result by compensating a measurement value obtained by the measurement using the stylus 11 based on a processed signal obtained by applying a low-pass filter to the detection signal output from the temperature sensor 124.

[0046] In the first embodiment, the measurement result is calculated by compensating the measured value based on the processed signal obtained by applying the low-pass filter to the detection signal. Thus, it is possible to calculate the measurement result corresponding to the actual strain of the entire probe 10, rather than the sharp temperature change caused by the temperature sensor 124. Accordingly, the probe coordinate compensation section 226 can output the compensated probe coordinates with high accuracy immediately after the power source of the coordinate measuring machine 1 is switched from OFF to ON, thus enabling the PC 40 to calculate the measurement result with a small measurement error.

[0047] In the first embodiment, the low-pass filter is a filter program recorded in the memory 21. The processor 22 is configured to read and execute the filter program and generate the processed signal by performing the arithmetic operation for applying the low-pass filter to the detection signal output from the temperature sensor 124.

[0048] This eliminates the need to separately provide a low-pass filter circuit, simplifying the structure of the coordinate measuring machine 1. Furthermore, such a structure facilitates updating the filter program. For example, the filter program can be updated depending on the installation environment of the coordinate measuring machine 1, the replacement of the entire probe 10 or the pin 11, or the like, allowing the time constant τ to be updated to an optimal value as needed.

[0049] In the first embodiment, the probe 10 including the pin 11 configured to contact the measurement target and the support 12 supporting the pin 11 serves as the measurement performing unit of the present disclosure, and the electrical section 122 and the temperature sensor 124 are arranged in the support 12 of the probe 10.

[0050] Such a probe 10 is capable of performing the appropriate compensation operation corresponding to the strain of the entire probe 10, as described above. Furthermore, only in the first embodiment is it necessary to provide the single temperature sensor 124. This structure is simpler than a structure in which the temperature sensors are arranged for the respective parts of the probe 10, such as the pin 11. Furthermore, the temperature sensor 124 does not interfere with the measurement target and other components of the coordinate measuring machine 1, and the wiring of the temperature sensor 124 is also simplified. Second embodiment

[0051] Next, a second embodiment will be described. In the first embodiment, the low-pass filter is a software program. The processor 22 of the controller 20 reads and executes the filter program in the memory 21 to function as a filter applying section 225, which applies the low-pass filter to the detection signal output from the temperature sensor 124 (arithmetic operation). On the other hand, a case where a low-pass filter circuit is used is given as an example in the second embodiment.

[0052] Fig. Figure 6 illustrates a schematic configuration of a coordinate measuring machine 1A of the second embodiment. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals to simplify or omit the description of the components.

[0053] The coordinate measuring machine 1A of the second embodiment includes the probe 10, the controller 20 and the PC 40 as in the first embodiment.

[0054] In the probe 10 of the second embodiment, the electrical section 122, which is the electrical circuit board, is further provided with a low-pass filter circuit 125. A detection signal output from the temperature sensor 124 is input to the low-pass filter circuit 125, and a processed signal output from the low-pass filter circuit 125 is input to the controller 20.

[0055] Fig. 7A to Fig. 7D are each an example of the low-pass filter circuit 125. The low-pass filter circuit 125 is not particularly limited. For example, an RC low-pass filter circuit as shown in Fig. 7A. In addition, exemplary circuits that can be used include an LC low-pass filter circuit as shown in Fig. 7B, a low-pass filter circuit using an operational amplifier as in Fig. 7C, and an LR low-pass filter circuit as shown in Fig. 7D. The examples of the low-pass filter circuit 125 shown in Fig. 7A to Fig. 7D differ in the time constant τ. However, all examples of the low-pass filter circuit 125 in Fig. 7A to Fig. 7D is able to convert the detection signal input from the temperature sensor 124 to the Fig. 4 and output the processed signal.

[0056] The low-pass filter circuit 125 is provided in the second embodiment. Thus, the processor 22 of the controller 20 does not need to function as the filter applying section 225.

[0057] Thus, the processor 22 in the second embodiment functions as a processed signal acquisition section 224A rather than the temperature acquisition section 224 in the first embodiment. The processed signal acquisition section 224A acquires a processed signal input from the temperature sensor 124 to the controller 20 via the low-pass filter circuit 125, that is, a processed signal after the low-pass filtering process. The probe coordinate compensation section 226 then outputs a measurement result obtained by compensating a measured value based on a temperature T L which corresponds to the processed signal detected by the processing signal detecting section 224A. Functions and effects of the second embodiment

[0058] The coordinate measuring machine 1A of the second embodiment achieves functions and effects similar to those of the first embodiment.

[0059] Furthermore, in the coordinate measuring machine 1A of the second embodiment, the processed signal is generated by processing the detection signal from the temperature sensor 124 in the low-pass filter circuit 125. Thus, it is possible to reduce the load on the arithmetic operation of the processor 22. Third embodiment

[0060] In the first embodiment, the example is given in which the processor 22 of the controller 20 functions as the filter applying section 225. In a third embodiment, an example is given in which the filter applying section 225 is provided in the probe 10.

[0061] Fig. 8 illustrates a schematic configuration of a coordinate measuring machine 1B according to the third embodiment.

[0062] In the Fig. In the coordinate measuring machine 1B illustrated in FIG. 8, an arithmetic processor 126 is provided for the electrical section 122 of the probe 10. The arithmetic processor 126 functions as the temperature detection section 224 and the filter application section 225 by executing software program(s). The functions of the temperature detection section 224 and the filter application section 225 are the same as those in the first embodiment. Specifically, the temperature detection section 224 detects a detection signal corresponding to a measurement temperature output from the temperature sensor 124 and outputs the detection signal to the filter application section 225. The filter application section 225 applies low-pass filtering to the detection signal input thereto and outputs a processed signal after the low-pass filtering to the controller 20.

[0063] Furthermore, similar to the second embodiment, the processor 22 of the controller 20 functions as the processed signal acquisition section 224A to acquire the processed signal after the low-pass filtering process. The probe coordinate compensation section 226 then outputs a measurement result obtained by compensating a measured value based on a temperature T L which corresponds to the processed signal detected by the processing signal detecting section 224A.

[0064] The third embodiment described above achieves functions and effects similar to those of the first and second embodiments. Fourth embodiment

[0065] In the third embodiment, the example is given in which the filter applying section 225 is provided in the probe 10. However, the filter applying section 225 may be provided in any part of the coordinate measuring machine. In a fourth embodiment, an example is given in which the filter applying section 225 is provided for the PC 40.

[0066] Fig. 9 illustrates a schematic configuration of a coordinate measuring machine 1C according to the fourth embodiment.

[0067] For example, in the Fig.In the coordinate measuring machine 1C illustrated in Figure 9, a PC processor 41 provided for the PC 40 functions as the filter applying section 225 and the probe coordinate compensating section 226 by executing software program(s). In this case, the temperature detecting section 224 of the controller 20 detects a detection signal corresponding to a temperature measured by the temperature sensor 124 and transmits the detection signal to the PC 40. The controller 20 also transmits measurement coordinates detected by the measurement coordinate detecting section 222 and probe coordinates detected by the probe coordinate detecting section 223 to the PC 40.

[0068] The filter applying section 225 of the PC 40 receives a detection signal from the controller 20 and applies the low-pass filtering process to the detection signal to generate a processed signal, as in the first embodiment.

[0069] The probe coordinate compensating section 226 receives the measurement coordinates and probe coordinates from the controller 20 and compensates a measured value based on the processed signal after the low-pass filtering process to calculate a measurement result.

[0070] The fourth embodiment described above achieves functions and effects similar to those of the first to third embodiments. Modifications

[0071] It should be noted that the invention is not limited to the above embodiments and includes the following modifications as long as the object of the invention can be achieved. Modification 1

[0072] In each of the above embodiments, the example is given in which the probe 10 including the pin 11 functions as the measurement performing unit, and the temperature of the probe 10 is measured by the temperature sensor 124 provided for the electrical section 122 built into the substrate 12 of the probe 10. However, the invention is not limited to this.

[0073] For example, temperatures of the X-scale 31, the Y-scale 32, and the Z-scale 33 in the coordinate measuring machines 1, 1A, 1B, and 1C can be measured by the measurement execution unit and then compensated. In this case, the X-scale 31 includes, for example, a scale with scale markings and an electrical section (detection head) equipped with an encoder or the like that reads the scale markings of the scale. A temperature sensor is provided for the detection head, which is the electrical section. Low-pass filtering is applied to a detection signal output from the temperature sensor to generate a processed signal, and a measured value measured by the X-scale 31 is compensated based on the processed signal.

[0074] The provision of the temperature sensor for the electrical section, which is the heat source, makes it possible to correctly compensate the measured value to correspond to an expansion of the entire X-scale 31, even if the temperature of the temperature sensor is different from that in each part of the X-scale 31.

[0075] The same applies to the Y-scale 32 and the Z-scale 33.

[0076] The above is an example of the X-scale 31, the Y-scale 32, and the Z-scale 33 provided for the coordinate measuring machines 1, 1A, 1B, and 1C. Such an example is also applicable to any other measuring device. For example, in a length measuring machine that measures a length of a measurement target in one direction (X-direction), the length of the measurement target is measured by a scale (measurement performing unit) arranged along a longitudinal direction. In this case, an electrical section provided in a part of the scale (for example, a reader that reads a value of the scale, such as an encoder) may include a temperature sensor, the low-pass filter may be applied to a detection signal output from the temperature sensor to generate a processed signal, as in the first and second embodiments, and the length measured by the scale (the measured value) may be compensated based on the processed signal. Modification 2

[0077] In the second embodiment, the example is given in which the low-pass filter circuit 125 is provided for the electrical section 122 incorporated into the carrier 12 of the probe 10. However, the invention is not limited thereto.

[0078] The low-pass filter circuit may be provided for any transmission circuit through which a signal from the temperature sensor 124 is transmitted to the controller 20. For example, the low-pass filter circuit 125 may be provided for a circuit board on which the processor 22 of the controller 20 is provided, to be connected to an input terminal to which a detection signal from the temperature sensor 124 is input. Modification 3

[0079] In the first embodiment, the example is given in which the filter applying section 225 detects the temperature T Lafter the low-pass filtering process based on formula (2). However, the invention is not limited thereto.

[0080] For example, a moving average represented by formula (3) can be used instead of formula (2). TL[n]=Ts[n]+Ts[n−1]+Ts[n−2]+⋯+Ts[n−i]i+1

[0081] In the first embodiment, a reverse difference system represented by formula (2) is used as a method for converting the low-pass filtering process for an analog signal into a digital signal. However, other formulas such as a bilinear transform and a pulse-invariant method are also usable. For example, formula (4) can be used for a first-order low-pass filter using the bilinear transform. TL[n]=A×Ts[n]−A×Ts[n−1]−B×Ts[n−1] where A=ΔtΔt+2τB=Δt−2τΔt+2τ

[0082] In formula (4), Δt represents a sampling period and τ represents a time constant. The intensity of the low-pass filter can be determined by the time constant τ.

[0083] The same applies to the third and fourth embodiments, in which the low-pass filtering operation is carried out by executing the software program(s).

[0084] The following is further disclosed with respect to the embodiments including the above examples.

[0085] [1] A measuring device comprising: a measurement performing unit configured to perform a measurement operation on a measurement target; an electrical section arranged in a part of the measurement performing unit; a temperature sensor provided for the electrical section and configured to output a detection signal based on a temperature obtained by measurement; and a measurement calculator configured to calculate a measurement result of the measurement target, wherein the measurement calculator is configured to calculate the measurement result by compensating a measurement value obtained by the measurement operation based on a processed signal obtained by applying a low-pass filter to the detection signal output from the temperature sensor.

[0086] In such a configuration, the temperature sensor measures the temperature of the electrical section, which is a heat source. For example, the temperature of the temperature sensor changes dramatically immediately after the power source of the measuring device is turned on. However, it is possible to convert the detection signal corresponding to the sharp temperature change and whose signal value changes dramatically into the processed signal whose signal value changes gradually by applying a low-pass filter to the detection signal output from the temperature sensor. Compensating the measured value based on the processed signal enables the compensation process corresponding to the slower temperature change in the measurement unit. That is, it is possible to perform the appropriate compensation process corresponding to the actual temperature in the measurement unit.

[0087] [2] The measuring device according to [1], wherein the low-pass filter is a filter program recorded in a memory, and the measuring computer is configured to read and execute the filter program recorded in the memory and calculate the processed signal by applying the low-pass filter to the detection signal output from the temperature sensor.

[0088] Such a design eliminates the low-pass filter circuit that converts the detection signal from the temperature sensor into the processed signal, simplifying the design of the measuring device. Furthermore, such a design facilitates updating the filter program, and the program can be updated to obtain the measurement result with high accuracy, regardless of changes in the installation environment of the measuring device, replacement of the measurement unit, etc.

[0089] [3] The measuring device according to [1], wherein the low-pass filter is a low-pass filter circuit, and the detection signal output from the temperature sensor is to be input into the low-pass filter circuit, and the processed signal output from the low-pass filter circuit is to be input into the measuring computer.

[0090] In this setup, the processed signal is generated by processing the detection signal from the temperature sensor in the low-pass filter circuit. Thus, the measurement computer does not need to perform the arithmetic operation related to the low-pass filter, thereby reducing the processing load related to the calculation.

[0091] [4] The measuring device according to [1], wherein the measurement performing unit is a probe including a pin configured to contact the measurement target and a support supporting the pin, and the electrical section and the temperature sensor are arranged in the support.

[0092] Such a probe, which includes the pin and the support, performs the measurement process by bringing the pin into contact with the measurement target. Here, the temperature sensor in the probe, which houses the temperature sensor for the electrical section, measures the temperature of the electrical section, which is the heat source. However, it takes a long time for heat to spread to every part of the probe, causing the temperature increase to become slow over time. Furthermore, the heat dissipates more rapidly with increasing distance from the electrical section, resulting in a decrease in the saturation temperature. Thus, the expansion of the entire probe due to the temperature increase cannot be directly compensated by the steeply rising temperature measured by the temperature sensor.In contrast, in this aspect of the invention, the measured value is compensated based on the processed signal obtained by applying the low-pass filter to the detection signal corresponding to the temperature measured by the temperature sensor. This makes it possible to perform the appropriate compensation process corresponding to the strain of the entire probe. Furthermore, in the structure in which the temperature sensor for the electrical section is arranged in the substrate as in this aspect of the invention, it is possible to reduce the number of temperature sensors compared to a case where the temperature sensors are arranged for respective parts of the probe, such as the pin, to prevent the temperature sensor from interfering with the measurement target and other components of the measuring device and to simplify the wiring arrangement of the temperature sensor. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2005-181293 A

[0002]

Claims

[1] Measuring device (1), comprising: a measurement execution unit (10) configured to perform a measurement operation on a measurement target; an electrical section (122) arranged in a part of the measurement implementation unit (10); a temperature sensor (124) provided for the electrical section (122) and configured to output a detection signal based on a temperature obtained by measurement; and a measurement computer (20) configured to calculate a measurement result of the measurement target, wherein the measuring computer (20) is configured to calculate the measurement result by compensating a measured value obtained by the measuring process on the basis of a processed signal resulting from applying a low-pass filter to the detection signal output by the temperature sensor (124). [2] Measuring device (1) according to claim 1, wherein the low-pass filter is a filter program recorded in a memory (21), and the measuring computer (20) is configured to read and execute the filter program recorded in the memory (21) and to calculate the processed signal by applying the low-pass filter to the detection signal output by the temperature sensor (124). [3] Measuring device (1) according to claim 1, wherein the low-pass filter is a low-pass filter circuit (125), and the detection signal output by the temperature sensor (124) is to be input into the low-pass filter circuit (125), and the processed signal output by the low-pass filter circuit (125) is to be input into the measuring computer (20). [4] Measuring device (1) according to claim 1, wherein the measurement performing unit (10) is a probe (10) comprising a pin (11) configured to contact the measurement target and a support (12) supporting the pin (11), and the electrical section (122) and the temperature sensor (124) are arranged in the carrier (12).

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