Calibration method and calibration apparatus

Abstract

To provide a calibration method and a calibration device capable of accurately performing calibration or the like at an arbitrary temperature without installing a thermometer.SOLUTION: The calibration method for the measuring apparatus 1 including the measuring arm 18 swingably supported by the swing fulcrum 20, the stylus 12 provided at the distal end of the measuring arm 18, the X-axis driving mechanism 60 configured to move the measuring arm 18 in the X direction, the X-axis detector 62 configured to detect the amount of movement of the measuring arm 18 in the X direction, and the Z-axis detector 22 configured to detect the amount of displacement of the measuring arm 18 in the Z direction includes the calibration step of calculating the calibration parameters of the measuring apparatus 1 using the first calibration gauge (the second block gauge 74 and the ball gauge 76) made of the low thermal expansion material.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a calibration method and a calibration device, and more particularly to a calibration method and a calibration device for a measuring device for measuring the shape, roughness, contour, etc. of the surface of a measurement object. [Background technology]

[0002] Measuring devices for measuring the shape, roughness, contour, etc. of the surface of a measurement object are known (see, for example, Patent Document 1). Such measuring devices include a measurement arm swingably supported on a fulcrum (swing axis), a stylus attached to the tip of the measurement arm, an X-axis detector that detects the amount of movement of the measurement arm in the X direction, and a Z-axis detector that detects the swing of the measurement arm as a displacement in the Z direction. When measuring the measurement object, the measurement arm is moved in the X direction with the stylus in contact with the surface of the measurement object. As a result, the X-axis detector and Z-axis detector detect the amount of movement and displacement of the measurement arm in the X direction and the Z direction, respectively, while the stylus traces the surface of the measurement object in the X direction. The position of the tip of the stylus (X coordinate value and Z coordinate value) is calculated from these detection results to obtain measurement data for the measurement object.

[0003] Here, the X-axis detector and Z-axis detector do not directly detect the tip position of the stylus. Furthermore, if the tip position of the stylus is displaced in the Z direction due to the arc motion caused by the swinging of the measurement arm, a measurement error (arc error) occurs in the X direction. Therefore, if the parameters required to calculate the tip position of the stylus, such as the arm length (the length from the fulcrum to the tip of the measurement arm) and the stylus height, deviate from their design values ​​due to manufacturing errors or other factors, the tip position of the stylus cannot be determined accurately, which can lead to a decrease in measurement accuracy. Therefore, in order to maintain measurement accuracy, the above-mentioned measuring device requires calibration.

[0004] In calibration of a measuring device, calibration parameters (arm length, stylus height, and stylus tip radius) are determined by comparing measurement data obtained by tracing a calibration gauge with known reference dimensions with the reference dimensions of the calibration gauge. Then, when measuring an object, the measurement data is calculated using the calibration parameters. This makes it possible to obtain highly accurate measurement results for the object. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-003436 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-mentioned measuring device, if calibration is performed in an environment where the ambient temperature is different from the reference temperature (for example, 20°C), the calibration gauge will thermally expand due to the temperature change from the reference temperature, making it impossible to perform calibration accurately. Therefore, to ensure calibration accuracy, it is preferable to perform calibration in an environment at the reference temperature, but performing calibration in such an environment is problematic in reality.

[0007] In response to this, it is conceivable to install a thermometer to detect the ambient temperature of the measuring device, and perform calibration based on the detection result of the thermometer, taking into account the effect of temperature changes (thermal expansion) on the calibration gauge.

[0008] However, installing a thermometer in a measurement device is not desirable because it leads to problems such as increased costs and increased maintenance load. Also, depending on the location of the thermometer, it may not always be possible to accurately measure the temperature of the thermally expanded component (calibration gauge), and there is a limit to how much calibration accuracy can be improved.

[0009] Furthermore, if the ambient temperature deviates from the reference temperature, the scales used in the X-axis detector and Z-axis detector will thermally expand due to the temperature change from the reference temperature, which will increase the error in the detected values ​​of the X-axis detector and Z-axis detector, resulting in a decrease in measurement accuracy.

[0010] The present invention has been made in view of the above circumstances, and has as its object to provide a calibration method and calibration device that can perform calibration etc. at any temperature with high accuracy without installing a thermometer. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention comprises the following aspects.

[0012] A calibration method according to a first aspect is a method for calibrating a measuring device that includes a measuring arm that is swingably supported on a fulcrum, a stylus provided at the tip of the measuring arm, a movement mechanism that moves the measuring arm in the X direction, a first detector that detects the amount of movement of the measuring arm in the X direction, and a second detector that detects the amount of displacement of the measuring arm in the Z direction, and includes a calibration step of calculating calibration parameters of the measuring device using a first calibration gauge made of a low-thermal expansion material.

[0013] The calibration method according to a second aspect is the same as that according to the first aspect, except that the thermal expansion coefficient of the low thermal expansion material is 1.2×10 -6 / K or less.

[0014] The calibration method according to the third aspect is the first or second aspect, and includes a temperature calculation step of calculating an ambient temperature of the measurement device using a second calibration gauge made of a material different from the low thermal expansion material, and a determination step of determining a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector based on the ambient temperature calculated in the temperature calculation step.

[0015] A calibration method according to a fourth aspect is in the first or second aspect and includes a temperature calculation step of calculating an ambient temperature of the measurement device based on measurement data of the first calibration gauge and the dimensions and thermal expansion coefficient of the calibration parameters at a reference temperature, and a determination step of determining a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector based on the ambient temperature calculated in the temperature calculation step.

[0016] A calibration device according to a fifth aspect is a calibration device for a measuring device that includes a measuring arm that is swingably supported on a fulcrum, a stylus provided at the tip of the measuring arm, a movement mechanism that moves the measuring arm in the X direction, a first detector that detects the amount of movement of the measuring arm in the X direction, and a second detector that detects the amount of displacement of the measuring arm in the Z direction, and includes a calibration processing unit that calculates calibration parameters of the measuring device based on measurement data of the first calibration gauge that is made of a low-thermal expansion material and obtained by measuring the first calibration gauge with the measuring device.

[0017] A sixth aspect of the present invention provides a calibration device according to the fifth aspect, wherein the low thermal expansion material has a thermal expansion coefficient of 1.2×10 -6 / K or less.

[0018] The calibration device of the seventh aspect is the fifth or sixth aspect, and includes a temperature calculation unit that calculates the ambient temperature of the measurement device based on measurement data of a second calibration gauge obtained by measuring the second calibration gauge made of a material different from the low thermal expansion material using the measurement device, and a temperature correction parameter determination unit that determines a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector based on the ambient temperature calculated by the temperature calculation unit.

[0019] The calibration device according to an eighth aspect is the same as that of the fifth or sixth aspect, and includes a temperature calculation unit that calculates the ambient temperature of the measurement device based on the measurement data of the first calibration gauge and the dimensions and thermal expansion coefficient of the calibration parameters at a reference temperature, and a temperature correction parameter determination unit that determines a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector based on the ambient temperature calculated by the temperature calculation unit. [Effects of the Invention]

[0020] According to the present invention, calibration and the like can be performed with high accuracy at any temperature without installing a thermometer. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram showing a measurement device according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of a control device. [Figure 3] FIG. 10 is a diagram for explaining calibration parameters. [Figure 4] FIG. 1 is a schematic diagram showing how the measurement device is calibrated. [Figure 5] FIG. 2 is a schematic diagram showing an enlarged view of a calibrator. [Figure 6] FIG. 10 is a diagram showing the state when the stylus traces the calibrator when calibration is performed. [Figure 7] FIG. 2 is a schematic diagram showing the main parts of a detector. [Figure 8] FIG. 1 is a schematic diagram illustrating the effect of thermal expansion on a calibrator ball gauge. [Figure 9] 5A and 5B are diagrams for explaining a method of calculating an ambient temperature performed by a temperature calculation unit. [Figure 10] 10 is a graph showing the characteristics of the indication accuracy of measurement axis detectors (X-axis detector and Z-axis detector). [Figure 11] 10 is a flowchart showing the flow of a method for calibrating a measurement device. [Figure 12] FIG. 10 is a schematic diagram showing a calibrator used in the second embodiment. [Figure 13] FIG. 10 is a block diagram showing the configuration of a control device according to a second embodiment. [Figure 14] FIG. 10 is a diagram showing the dimensional relationship between the measurement arm and the stylus before and after thermal expansion when the ambient temperature changes from the reference temperature. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0023] First Embodiment [Measuring equipment] 1 is a schematic diagram showing a measurement device according to the first embodiment. In the following description, a three-dimensional Cartesian coordinate system is used in which the XY plane is the horizontal plane and the Z direction is the vertical direction (perpendicular direction).

[0024] The measuring device 1 is a device for measuring the shape, roughness, contour, etc. of the surface of a measuring object W placed on a measuring object placement section (hereinafter referred to as a stage) 50.

[0025] 1, the stage 50 is placed on a base 52, and the surface of the stage 50 (the surface on which the measurement target W is placed) is parallel to the XY plane. A column (Z-axis) 54 extending approximately perpendicular to the surface of the stage 50 is placed on the base 52. A carriage (X-axis) 56 is attached to the column 54, and the carriage 56 can be moved in the Z direction along the column 54 by a Z-axis drive mechanism 58 (see FIG. 2), such as an actuator.

[0026] The detector 10 is attached to the carriage 56, and the detector 10 is movable in the X direction relative to the carriage 56 by an X-axis drive mechanism 60 (see FIG. 2) such as an actuator. The carriage 56 is provided with an X-axis detector 62 for detecting the amount of movement of the detector 10 (a measuring arm 18 described below) in the X direction. The X-axis detector 62 is an example of a "first detector" in the present invention. The X-axis drive mechanism 60 is also an example of a "moving mechanism" in the present invention.

[0027] The X-axis detector 62 is composed of a scale 64 and a read head (not shown). The scale 64 is, for example, a linear scale (linear position scale) with multiple graduations formed along its length. The X-axis detector 62 detects the amount of movement of the detector 10 in the X direction by reading the graduations of the scale 64 with the read head. The detection value of the X-axis detector 62 is output to the control device 100.

[0028] The reading head constituting the X-axis detector 62 may be, for example, a photoelectric sensor for reading the graduations of the scale 64 or a non-contact sensor equipped with an imaging element and an illumination light source (for example, an LED (Light-Emitting Diode)). Note that the type of reading head is not limited to the above.

[0029] In this embodiment, the detector 10 is movable relative to the column 54, but this is not limiting. For example, the column 54 may be movable along the X direction relative to the stage 50, or the stage 50 may be movable along the X or Z direction relative to the column 54. That is, it is sufficient that the measurement object W placed on the stage 50 and the detector 10 are configured to be relatively movable in the X and Z directions. Furthermore, the detector 10 may be configured to be relatively movable not only in the X direction but also in the Y direction relative to the measurement object W placed on the stage 50.

[0030] As shown in FIG. 1, the detector 10 includes a stylus 12 , a measuring arm 18 , a swing support 20 , and a Z-axis detector 22 .

[0031] The measurement arm 18 is supported so as to be swingable around a swing fulcrum 20 provided inside the detector housing 28. Specifically, the measurement arm 18 is composed of a first arm portion 16 swingably supported on the swing fulcrum 20, and a second arm portion 14 replaceably attached to the tip of the first arm portion 16 via a detachable mechanism (not shown). The mounting angle of the swing fulcrum 20 relative to the carriage 56 of the detector 10 is adjusted so that it is approximately parallel to the XY plane.

[0032] A stylus 12 is provided at the tip of the measurement arm 18 (second arm portion 14). The stylus 12 extends downward (in the -Z direction) in the figure. With the stylus 12 in contact with the surface of the measurement object W placed on the stage 50 with a predetermined pressure, when the measurement arm 18 is moved in the X direction by moving the detector 10 in the X direction, the measurement arm 18 swings around a swing fulcrum 20 in accordance with the position in the Z direction of the surface of the measurement object W at the contact position of the stylus 12.

[0033] The configuration of second arm unit 14 is not limited to the example shown in Fig. 1. For example, it may be a T-shaped stylus in which the stylus is provided in the vertical direction of second arm unit 14 in the drawing, or an L-shaped stylus in which the amount of protrusion of the stylus downward in the drawing is longer than in the example shown in Fig. 1.

[0034] The Z-axis detector 22 is composed of a scale 24 and a read head 26. The scale 24 is fixed inside the detector housing 28 via a scale mounting member 30 (see FIG. 7) described below so as to face the base end of the measuring arm 18 (first arm portion 16).

[0035] The scale 24 is, for example, a linear scale (linear position scale) with multiple graduations formed along the length of the scale 24. The scale 24 is attached so that its length (displacement detection direction) is approximately perpendicular to the length of the measuring arm 18.

[0036] The read head 26 is fixed to the base end of the measurement arm 18 (first arm portion 16) and is capable of swinging integrally with the measurement arm 18. The read head 26 is a device that reads the scale (hereinafter referred to as the indicated value) at the opposite position on the scale 24 fixed to the detector housing 28. As the read head 26, for example, a photoelectric sensor for reading the scale 24 or a non-contact sensor equipped with an imaging element and an illumination light source (for example, an LED (Light-Emitting Diode)) can be used. Note that the type of the read head 26 is not limited to the above.

[0037] The Z-axis detector 22 detects the displacement (swing amount) in the Z direction of the base end of the measuring arm 18 by reading the graduations of the scale 24 with the read head 26. The detected value of the Z-axis detector 22 is output to the control device 100. The Z-axis detector 22 is an example of the "second detector" of the present invention.

[0038] In this embodiment, the scale 24 is fixed to the detector housing 28, and the read head 26 is fixed to the base end of the measuring arm 18, but the present invention is not limited to this. For example, the read head 26 may be fixed to the detector housing 28, and the scale 24 may be fixed to the base end of the measuring arm 18. Furthermore, the scale 24 is not limited to a linear scale, and may be, for example, an arc scale (angle scale) formed in an arc shape along the swing direction of the measuring arm 18.

[0039] [Control device] Next, the configuration of the control device 100 will be described.

[0040] Fig. 2 is a block diagram showing the configuration of control device 100. As shown in Fig. 2, control device 100 includes a control unit 102, an input unit 104, a display unit 106, and a storage 108. In addition, an X-axis drive mechanism 60, a Z-axis drive mechanism 58, an X-axis detector 62, and a Z-axis detector 22 are connected to control device 100. Control device 100 also includes a calibration function, as will be described later, and is an example of the "calibration device" of the present invention.

[0041] The control unit 102 includes a processor (e.g., a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit)) and a memory (e.g., a ROM (Read Only Memory), a RAM (Random Access Memory)). The control unit 102 controls each unit and executes calculation processing in response to an operation input from the input unit 104.

[0042] The input unit 104 is a device for receiving operation input from an operator, and includes, for example, a keyboard, a mouse, a touch panel, and the like.

[0043] The display unit 106 is a device for displaying images and includes, for example, an LCD (Liquid Crystal Display). The display unit 106 displays, for example, a GUI (Graphical User Interface) for operating each part of the measuring device 1 and measurement results such as the shape, roughness, or contour of the surface of the measurement target W.

[0044] The storage 108 is a device that stores a control program for controlling the measurement device 1, measurement result data, and the like, and includes, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0045] The control unit 102 reads and executes a control program stored in the storage 108, thereby functioning as a drive control unit 110, a calibration processing unit 112, a temperature calculation unit 114, a temperature correction parameter determination unit 116, and a measurement processing unit 118. Each unit will be described in detail below.

[0046] (Drive control unit) The drive control unit 110 controls the driving of the X-axis drive mechanism 60 and the Z-axis drive mechanism 58. Specifically, the drive control unit 110 controls the driving of the Z-axis drive mechanism 58 to move (raise and lower) the carriage 56 in the Z direction relative to the column 54. The drive control unit 110 also controls the driving of the X-axis drive mechanism 60 to move the detector 10 in the X direction relative to the carriage 56.

[0047] (Calibration processing unit) The calibration processing unit 112 calculates calibration parameters of the measuring device 1 by comparing measurement data (actual measurements) of a calibrator M (see FIG. 5) described below, obtained by measuring the calibrator M with the measuring device 1, with reference dimensions (known) of the calibrator M stored in advance in the storage 108. As shown in FIG. 3, the calibration parameters include the arm length LH (the length in the X direction from the swing support 20 to the tip of the stylus), the stylus height LV (the length in the Z direction from the swing support 20 to the tip of the stylus), and the radius R of the tip of the stylus.

[0048] In the measuring apparatus 1 of this embodiment, the stylus 12 is provided at the tip of a measuring arm 18 that is supported so as to be swingable about a swing fulcrum 20, and a Z-axis detector 22 that detects the displacement of the measuring arm 18 in the Z direction is provided at the base end of the measuring arm 18. For example, if any of the arm length LH, stylus height LV, and stylus tip radius R deviates from the design value due to manufacturing errors or the like, the tip position of the stylus 12 cannot be accurately determined, which can result in measurement errors. Therefore, to maintain measurement accuracy in the measuring apparatus 1, it is necessary to determine calibration values ​​(hereinafter referred to as "calibration parameters") obtained by calibrating the arm length LH, stylus height LV, and stylus tip radius R, respectively. This eliminates measurement errors caused by manufacturing errors of the measuring arm 18 and the stylus 12.

[0049] The calibration parameters obtained by the calibration processing unit 112 are stored in the storage 108 and are used when the measurement data of the measurement object W is obtained by the measurement processing unit 118, which will be described later.

[0050] (calibrator) Here, the calibrator M used in this embodiment will be described.

[0051] Fig. 4 is a schematic diagram showing how the measurement device 1 is calibrated. Fig. 5 is a schematic diagram showing an enlarged view of the calibrator M shown in Fig. 4. As shown in Fig. 4, when the measurement device 1 is calibrated, the calibrator M is placed on the stage 50.

[0052] As shown in FIG. 5, rectangular parallelepiped block gauges 72 and 74 (hereinafter referred to as the "first block gauge 72" and the "second block gauge 74") and a hemispherical ball gauge 76 are provided on an upper surface 70a (reference surface) of a reference block 70 that constitutes the base portion of the calibrator M. The upper surface 70a of the reference block 70 and the upper surface 72a of the first block gauge 72 are parallel to each other, and the distance between them, i.e., the step dimension, is known. The upper surface 70a of the reference block 70 and the upper surface 74a of the second block gauge 74 are parallel to each other, and the distance between them, i.e., the step dimension, is known. The surface 76a of the ball gauge 76 is spherical, and its radius is known.

[0053] The first block gauge 72 is made of a normal material (a material other than a low thermal expansion material, which will be described later). For example, steel is used as the normal material. For example, normal steel (thermal expansion coefficient 11.5×10) as specified in JIS B 7506 (2004) is used as the steel. 6 / K). The first block gauge 72 is an example of the "second calibration gauge" of the present invention. JIS is an abbreviation for Japanese Industrial Standards.

[0054] The second block gauge 74 and the ball gauge 76 are made of a low thermal expansion material such as quartz glass or ceramics. -6 / K or less. An example of such a low thermal expansion material is NEXCERA (registered trademark) (thermal expansion coefficient 0.03×10 -6 / K or less), and Clearceram (registered trademark) (thermal expansion coefficient 1±0.1×10 -6 The second block gauge 74 and the ball gauge 76 are examples of the "first calibration gauge" of the present invention.

[0055] Although the second block gauge 74 and the ball gauge 76 are preferably made of the same low thermal expansion material, this is not a limitation, and they may be made of different low thermal expansion materials.

[0056] In this manner, in the calibrator M used in this embodiment, the first block gauge 72 is made of a normal material, and the second block gauge 74 and the ball gauge 76 are made of a low thermal expansion material.

[0057] FIG. 6 is a diagram showing the state when the stylus 12 traces the calibrator M when calibration is performed.

[0058] As shown in VIA to VIC in FIG. 6, when the measuring device 1 is calibrated, the stylus 12 is traced against the upper surface 74a of the second block gauge 74, the upper surface 70a of the reference block 70, and the surface 76a of the ball gauge 76, respectively.

[0059] The calibration processing unit 112 acquires measurement data of the calibrator M, including the step dimension between the upper surface 74a of the second block gauge 74 and the upper surface 70a of the reference block 70, and the radius value of the ball gauge 76, from the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 obtained when tracing the stylus 12. Then, the calibration processing unit 112 calculates calibration parameters (arm length LH, stylus height LV, and radius value R of the stylus tip) by comparing the measurement data of the calibrator M with the reference dimensions (known) of the calibrator M stored in advance in the storage 108.

[0060] As described above, in this embodiment, calibration is performed based on the measurement data of the calibrator M obtained when the stylus 12 traces the second block gauge 74 and the ball gauge 76, which are made of a low-thermal expansion material, of the calibrator M. Therefore, even if calibration is performed in an environment where the ambient temperature is different from the reference temperature (e.g., 20°C), the second block gauge 74 and the ball gauge 76 are not affected (thermal expansion) by temperature changes from the reference temperature. Therefore, calibration can be performed at any temperature, and calibration accuracy can be ensured. Note that a known method (see, for example, Japanese Patent Application Laid-Open No. 10-332304) is applied to the calibration method using the block gauge (step gauge) and the ball gauge (reference sphere), and therefore a detailed description thereof will be omitted here.

[0061] 7 is a schematic diagram showing the main parts of the detector 10. As shown in Fig. 7, a scale mounting member 30 that connects the oscillating fulcrum 20 and the scale 24 is provided inside the detector 10. The scale mounting member 30 is a member that determines the distance between the oscillating fulcrum 20 and the scale 24.

[0062] If the ambient temperature differs from the reference temperature, the scale 24 will thermally expand in the Z direction (longitudinal direction of the scale) and the scale mounting member 30 will thermally expand in the X direction (axial direction of the measuring arm 18), which will affect the calibration of the measuring device 1.

[0063] Therefore, in this embodiment, it is preferable that the scale 24 and scale mounting member 30 are made of a low thermal expansion material. This makes it possible to ensure calibration accuracy even when calibration is performed at any temperature, since the scale 24 and scale mounting member 30 are little (almost negligible) affected by temperature changes. Note that the scale 24 and scale mounting member 30 may be made of the same low thermal expansion material as the second block gauge 74 and ball gauge 76 described above, or may be made of a different material.

[0064] Fig. 8 is a schematic diagram showing the thermal expansion of ball gauge 76 of calibrator M. As shown in Fig. 8, when calibration is performed at an arbitrary temperature, if ball gauge 76 thermally expands due to the influence of a temperature change from the reference temperature, the radius value R of the stylus tip will be calculated to be smaller than the original radius value (true value) by the amount of thermal expansion of ball gauge 76.

[0065] Therefore, in this embodiment, the ball gauge 76 is made of a low thermal expansion material to eliminate errors in the radius value R of the stylus tip due to thermal expansion of the ball gauge 76. This makes it possible to accurately determine the calibration value of the tip shape of the stylus 12 (radius value R of the stylus tip).

[0066] As described above, the calibration processing unit 112 of this embodiment determines the calibration parameters (arm length LH, stylus height LV, and stylus tip radius R) based on the measurement data of the calibrator M obtained when the stylus 12 traces the second block gauge 74 and ball gauge 76 made of a low thermal expansion material in the calibrator M. This makes it possible to perform calibration at any temperature, ensuring calibration accuracy while improving user convenience.

[0067] (Temperature calculation section) The temperature calculation unit 114 uses the first block gauge 72 of the calibrator M to calculate the ambient temperature of the measurement device 1.

[0068] 9 is a diagram for explaining a method of calculating the ambient temperature performed by the temperature calculation unit 114. As shown in FIG. 9, when the ambient temperature is calculated by the temperature calculation unit 114, the stylus 12 is traced on the upper surface 72a of the first block gauge 72 and the upper surface 70a of the reference block 70. Note that the measurement results obtained when tracing the upper surface 70a of the reference block 70 during calibration may be used. In this case, tracing the upper surface 70a of the reference block 70 is not necessary.

[0069] The temperature calculation unit 114 acquires measurement data (actual measurements) of the calibrator M, including the step dimension between the upper surface 72a of the first block gauge 72 and the upper surface 70a of the reference block 70, from the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 obtained when tracing the stylus 12. Then, the temperature calculation unit 114 calculates the amount of expansion of the first block gauge 72 based on the measurement data of the calibrator M and the reference step dimension (step dimension at a reference temperature) and linear expansion coefficient of the first block gauge 72 stored in advance in the storage 108.

[0070] Here, the step dimension of the first block gauge 72 obtained from the measurement data of the calibrator M is H′, the reference step dimension of the first block gauge 72 is H, the expansion amount of the first block gauge 72 is ΔH (=H′−H), and the linear expansion coefficient of the first block gauge 72 is α BG Furthermore, the reference temperature is T, the ambient temperature is T', and the difference between the ambient temperature T' and the reference temperature T is ΔT (= T' - T).

[0071] When defined as above, the expansion amount ΔH of the first block gauge 72 is calculated by the following formula (1).

[0072] ΔH=α BG ×H×ΔT (1)

[0073] By solving equation (1) for ΔT, we obtain the following equation (2).

[0074] ΔT=ΔH / (α BG ×H) (2)

[0075] Therefore, the ambient temperature T' can be calculated using the following equation (3). T′=T+ΔT =T+ΔH / (α BG ×H) ···(3)

[0076] In this way, the temperature calculation unit 114 in this embodiment can calculate the ambient temperature of the measuring device 1 according to the above formula (3) by utilizing the phenomenon in which the first block gauge 72 of the calibrator M, which is made of an ordinary material, thermally expands by an amount corresponding to a temperature change from the reference temperature. This makes it possible to easily and accurately determine the ambient temperature without installing a thermometer to detect the ambient temperature in the measuring device 1.

[0077] (Temperature correction parameter determination unit) The temperature correction parameter determination unit 116 determines temperature parameters for correcting the detection errors of the X-axis detector 62 and the Z-axis detector 22 based on the ambient temperature calculated by the temperature calculation unit 114 .

[0078] Here, if the ambient temperature is different from the reference temperature, the scales of the measurement axis detectors (X-axis detector 62 and Z-axis detector 22) will thermally expand due to the influence of the ambient temperature.

[0079] For example, if the scale 64 of the X-axis detector 62 thermally expands, an error occurs in the detected value X' actually detected by the X-axis detector 62 across the entire detection range of the X-axis detector 62, compared with the accurate detected value (true value) X detected by the X-axis detector 62 at the reference temperature. In this case, the following equation (4) holds true. X′=C X ×X ···(4) In addition, C X is a constant related to the X-axis indication accuracy with respect to the ambient temperature, and its unit is [μm / (mm·℃)].

[0080] Furthermore, when the scale 24 of the Z-axis detector 22 thermally expands, an error occurs in the detection value Z' actually detected by the Z-axis detector 22 across the entire detection range of the Z-axis detector 22, compared with the accurate detection value (true value) Z detected by the Z-axis detector 22 at the reference temperature. In this case, the following equation (5) holds: Z′=C Z ×Z (5) In addition, C Zis a constant related to the Z-axis indication accuracy with respect to temperature, and its unit is [μm / (mm·℃)].

[0081] FIG. 10 is a graph showing the characteristics of the indication accuracy of the measurement axis detectors (X-axis detector 62 and Z-axis detector 22). In FIG. 10, the horizontal axis indicates the detection position (stroke position) of the measurement axis detector, and the vertical axis indicates the detection accuracy of the measurement axis detector (error between the actual detected value and the true value). FIG. 10 shows a graph in which the ambient temperature changes by ±ΔT (°C) relative to the reference temperature, and the temperature correction parameter of the measurement axis detector is set to C (constant C of X-axis detector 62). X , and the constant C of the Z-axis detector 22 Z (corresponding to ), the slope of each graph is (C-1). Also, the temperature correction parameter C will be a different value for each ambient temperature.

[0082] By correcting the detection value at each detection position based on such temperature correction parameter C so that the detection error of the measurement axis detector is canceled, the detector indication accuracy becomes zero throughout the entire detection range, as shown by the solid line in the graph in Figure 10.

[0083] Therefore, in this embodiment, a temperature correction parameter C corresponding to each ambient temperature (i.e., the temperature correction parameter C of the X-axis detector 62) is set. X , and the temperature correction parameter C of the Z-axis detector 22 Z ) are prepared and stored in advance in storage 108.

[0084] Then, the temperature correction parameter determination unit 116 determines the temperature correction parameter C corresponding to the ambient temperature calculated by the temperature calculation unit 114 from among the plurality of temperature correction parameters C stored in the storage 108. The temperature correction parameter C determined by the temperature correction parameter determination unit 116 is output to the measurement processing unit 118, which will be described later.

[0085] The temperature correction parameter C may be stored as a table (lookup table) corresponding to the ambient temperature, or may be stored as a function (for example, an approximate curve obtained by least squares approximation or polynomial approximation) calculated from the temperature correction parameter C corresponding to the ambient temperature. When the temperature correction parameter C is stored as a table, the temperature correction parameter C corresponding to the ambient temperature can be obtained by performing interpolation, interpolation, or extrapolation based on the ambient temperature.

[0086] (Measurement processing unit) The measurement processing unit 118 calculates measurement data of the measurement object W from the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 obtained when the stylus 12 traces the surface of the measurement object W.

[0087] Specifically, the measurement processing unit 118 corrects the detection values ​​detected by the X-axis detector 62 and the Z-axis detector 22 based on the temperature correction parameter C determined by the temperature correction parameter determination unit 116 so as to cancel detection errors of the X-axis detector 62 and the Z-axis detector 22 caused by temperature changes from the reference temperature. Then, the measurement processing unit 118 calculates measurement data of the measurement object W based on the corrected detection values ​​of the X-axis detector 62 and the Z-axis detector 22 using the calibration parameters stored in the storage 108. This makes it possible to obtain highly accurate measurement data of the measurement object W even when the ambient temperature is different from the reference temperature.

[0088] [Measuring device calibration method] Next, a description will be given of a method for calibrating the measurement device 1 (including determining the temperature correction parameter C). Fig. 11 is a flowchart showing the flow of the method for calibrating the measurement device 1. As mentioned above, the calibration of the measurement device 1 can be performed at any temperature.

[0089] First, the calibrator M is placed on the stage 50 of the measuring device 1 (step S10).

[0090] Next, the measurement device 1 is calibrated using the low thermal expansion material gauges (second block gauge 74 and ball gauge 76) of the calibrator M (step S12). At this time, the calibration processing unit 112 calculates calibration parameters (arm length LH, stylus height LV, and radius value R of the stylus tip) based on measurement data (including the step dimension of the second block gauge 74 and the radius value of the ball gauge 76) obtained when the stylus 12 traces the second block gauge 74 and the ball gauge 76. The calibration processing unit 112 saves the calculated calibration parameters in storage 108. The calibration parameters saved in storage 108 are used when determining measurement data of the measurement object W.

[0091] Next, the ambient temperature of the measuring device 1 is calculated using the normal material gauge (first block gauge 72) of the calibrator M (step S14). At this time, the temperature calculation unit 114 calculates the ambient temperature of the measuring device 1 based on the measurement data of the first block gauge 72 (including the step dimension of the first block gauge 72) obtained when the stylus 12 traces the first block gauge 72, and the reference step dimension and linear expansion coefficient of the first block gauge 72 stored in the storage 108. The method of calculating the ambient temperature of the measuring device 1 is as described above.

[0092] Next, a temperature correction parameter C is determined based on the ambient temperature of the measurement device 1 to correct the detection errors of the X-axis detector 62 and the Z-axis detector 22. Specifically, the temperature correction parameter determination unit 116 determines the temperature correction parameter C corresponding to the ambient temperature calculated by the temperature calculation unit 114 from among a plurality of temperature correction parameters C stored in advance in the storage 108. The temperature correction parameter C is output to the measurement processing unit 118 and is used by the measurement processing unit 118 to correct the detection values ​​of the X-axis detector 62 and the Z-axis detector 22.

[0093] This completes the flowchart shown in FIG.

[0094] In the measurement device 1 of this embodiment, after calibration is performed at an arbitrary temperature as described above, measurement of the measurement target W is carried out.

[0095] In measuring the measurement object W, the drive control unit 110 controls the drive of the Z-axis drive mechanism 58 to adjust the position (height) of the detector 10 in the Z direction relative to the measurement object W, so that the stylus 12 is in contact with the surface of the measurement object W. Then, with the stylus 12 in contact with the surface of the measurement object W, the drive control unit 110 controls the drive of the X-axis drive mechanism 60 to move the detector 10 in the X direction, thereby moving the measurement arm 18 in the X direction. As a result, while the stylus 12 traces the surface of the measurement object W along the X direction, the movement amount of the detector 10 (measurement arm 18) in the X direction is detected by the X-axis detector 62, and the displacement amount of the measurement arm 18 in the Z direction is detected by the Z-axis detector 22.

[0096] When the measurement processing unit 118 acquires the detection values ​​of the X-axis detector 62 and the Z-axis detector 22, it corrects the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 based on the temperature correction parameter C determined by the temperature correction parameter determination unit 116. This corrects the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 so that detection errors of the X-axis detector 62 and the Z-axis detector 22 caused by the influence of temperature changes from the reference temperature are canceled out.

[0097] Then, the measurement processing unit 118 uses the calibration parameters (arm length LH, stylus height LV, and stylus tip radius R) stored in the storage 108 to determine measurement data of the measurement object W based on the corrected detection values ​​of the X-axis detector 62 and the Z-axis detector 22. The measurement data of the measurement object W is stored in the storage 108 and is output to the display unit 106 in response to a request (operation) from the user via the input unit 104.

[0098] As described above, according to this embodiment, the calibrator M is provided with low thermal expansion material gauges (second block gauge 74 and ball gauge 76), and the calibration parameters are determined using the low thermal expansion material gauges. Therefore, calibration can be performed at any temperature without installing a thermometer in the measurement device 1, improving user convenience.

[0099] Furthermore, according to this embodiment, the calibrator M is provided with a normal material gauge (first block gauge 72), and the detection errors of the X-axis detector 62 and the Z-axis detector 22 caused by temperature changes from the reference temperature are corrected based on the ambient temperature determined from the measurement data of the normal material gauge. Therefore, it is possible to obtain highly accurate measurement data of the measurement object W without being affected by the ambient temperature.

[0100] In this embodiment, the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 are corrected based on the temperature correction parameter C. However, for example, when the temperature correction parameter C is smaller than a predetermined threshold value (when the difference between the ambient temperature and the reference temperature is sufficiently small), the detection errors of the X-axis detector 62 and the Z-axis detector 22 can be considered to be substantially zero, and therefore correction of the detection values ​​of the X-axis detector 62 and the Z-axis detector 22 may not be performed.

[0101] Furthermore, in this embodiment, correction of the detection values ​​based on the temperature correction parameter C is performed for both the X-axis detector 62 and the Z-axis detector 22, but this is not limiting, and correction may be performed for only one of the X-axis detector 62 and the Z-axis detector 22. For example, as described above, if the scale 24 of the Z-axis detector 22 is made of a low thermal expansion material, there is little (almost no) effect from temperature changes from the reference temperature, so correction of the detection values ​​of the Z-axis detector 22 may not be performed and only correction of the detection values ​​of the X-axis detector 62 may be performed.

[0102] Furthermore, in this embodiment, temperature correction may be performed on the measurement data of the measurement object W obtained by the measurement processing unit 118 so that the influence of temperature changes from the reference temperature (thermal expansion) is canceled based on the ambient temperature calculated by the temperature calculation unit 114. This makes it possible to obtain measurement results of the measurement object W converted to the reference temperature.

[0103] Second Embodiment Next, a second embodiment will be described. Below, a description of the parts common to the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0104] Fig. 12 is a schematic diagram showing a calibrator M used in the second embodiment. As shown in Fig. 12, the calibrator M of the second embodiment differs from the first embodiment in that the first block gauge 72 (see Fig. 5) made of a normal material is not provided on the reference block 70, and only the second block gauge 74 and ball gauge 76 made of a low thermal expansion material are provided.

[0105] Fig. 13 is a block diagram showing the configuration of a control device 100A according to the second embodiment. As shown in Fig. 13, in the control device 100A according to the second embodiment, the control unit 102 includes a temperature calculation unit 114A. In addition, the dimensions (arm length LH, stylus height LV, and stylus tip radius R) and thermal expansion coefficient of each part of the stylus (measurement arm 18 and stylus 12) at the reference temperature are stored in the storage 108 as stylus information.

[0106] Although the configuration of the calibrator M is partially different from that of the first embodiment, the calibration processing unit 112 is similar to the first embodiment in that it determines calibration parameters (arm length LH, stylus height LV, and radius value R of the stylus tip) based on measurement data obtained when the stylus 12 traces the second block gauge 74 and ball gauge 76 of the calibrator M at any temperature.

[0107] The temperature calculation unit 114A calculates the ambient temperature of the measurement device 1 based on the stylus information stored in the storage 108 and the calibration parameters (arm length LH, stylus height LV, and radius value R of the stylus tip) determined by the calibration processing unit 112.

[0108] FIG. 14 is a diagram showing the dimensional relationship between the measurement arm 18 and the stylus 12 before and after thermal expansion when the ambient temperature changes from the reference temperature. Here, the reference temperature is T, the ambient temperature is T', and the difference between the ambient temperature T' and the reference temperature T is ΔT (=T'-T). The arm length at the reference temperature T is LH0, the stylus height is LV0, and the radius of the stylus tip is R0. The arm length at the ambient temperature T' is LH, the stylus height is LV, and the radius of the stylus tip is R. The linear expansion coefficient of the measurement arm 18 (the portion from the swing fulcrum 20 to the tip of the measurement arm 18: the portion corresponding to the arm length) is α H and the linear expansion coefficient of the stylus 12 is α V The linear expansion coefficient of the stylus tip is α R In this case, the following equation (6) holds true. LH=α H ΔT×LH0+LH0 (6)

[0109] By solving the above equation for ΔT, we obtain the following equation (7). ΔT=(LH-LH0) / (α H ×LH0) ···(7)

[0110] Therefore, the ambient temperature T can be calculated from the following equation (8). T′=T+ΔT =T+(LH-LH0) / (α H ×LH0) ···(8)

[0111] The temperature calculation unit 114A calculates the arm length LH0 and the linear expansion coefficient at the reference temperature acquired from the storage 108 according to the formula (8) as α H and the arm length LH calculated by the calibration processing unit 112, the ambient temperature T' can be calculated.

[0112] Here, as an example, the case where the ambient temperature is determined using the dimensional relationship between the arm length LH before and after thermal expansion has been shown, but this is not limiting, and the ambient temperature may also be determined using the relationship between the stylus height LV or the stylus tip radius R before and after thermal expansion.

[0113] The temperature correction parameter determination unit 116 and the measurement processing unit 118 are performed in the same manner as in the first embodiment.

[0114] According to the second embodiment, the calibrator M is provided with only low thermal expansion material gauges (the second block gauge 74 and the ball gauge 76), and the ambient temperature is determined from the measurement data of the low thermal expansion material gauges. Therefore, calibration and measurement can be performed at any temperature without installing a thermometer in the measurement device 1, improving user convenience.

[0115] Furthermore, according to the second embodiment, there is no need to provide a normal material gauge (first block gauge 72) as in the first embodiment, so the configuration of the calibrator M can be simplified and the calibration work can be made more efficient.

[0116] Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0117] 1...measuring device, 10...detector, 12...stylus, 14...second arm section, 16...first arm section, 18...measuring arm, 20...oscillating fulcrum, 22...Z-axis detector, 24...scale, 26...reading head, 28...detector housing, 30...scale mounting member, 50...measurement object placement section, 52...surface plate, 54...column, 56...carriage, 58...Z-axis drive mechanism, 60...X-axis drive mechanism, 62...X-axis detector, 64...scale, 70...reference block, 72...first block gauge, 74...second block gauge, 76...ball gauge, 100...control device, 102...control section, 104...input section, 106...display section, 108...storage, 110...drive control section, 112...calibration processing section, 114...temperature calculation section, 116...temperature correction parameter determination section, 118...measurement processing section

Claims

1. 1. A method for calibrating a measuring device including a measuring arm swingably supported on a fulcrum, a stylus provided at the tip of the measuring arm, a movement mechanism for moving the measuring arm in an X direction, a first detector for detecting an amount of movement of the measuring arm in the X direction, and a second detector for detecting an amount of displacement of the measuring arm in a Z direction, a calibration step of calculating calibration parameters of the measuring device using a first calibration gauge made of a low thermal expansion material; Calibration method.

2. The thermal expansion coefficient of the low thermal expansion material is 1.2×10 －６ / K or less, The calibration method according to claim 1 .

3. a temperature calculation step of calculating an ambient temperature of the measurement device using a second calibration gauge made of a material different from the low thermal expansion material; a determination step of determining a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector, based on the ambient temperature calculated in the temperature calculation step; The calibration method according to claim 1 or 2, comprising:

4. a temperature calculation step of calculating an ambient temperature of the measurement device based on the measurement data of the first calibration gauge and the dimensions and thermal expansion coefficient of the calibration parameters at a reference temperature; a determination step of determining a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector, based on the ambient temperature calculated in the temperature calculation step; The calibration method according to claim 1 or 2, comprising:

5. A calibration device for a measuring device comprising: a measurement arm supported swingably on a fulcrum; a stylus provided at the tip of the measurement arm; a movement mechanism for moving the measurement arm in an X direction; a first detector for detecting the amount of movement of the measurement arm in the X direction; and a second detector for detecting the amount of displacement of the measurement arm in the Z direction, a calibration processing unit that calculates calibration parameters of the measuring device based on measurement data of the first calibration gauge obtained by measuring the first calibration gauge made of a low thermal expansion material with the measuring device; Calibration device.

6. The thermal expansion coefficient of the low thermal expansion material is 1.2×10 －６ / K or less, The calibration device according to claim 5 .

7. a temperature calculation unit that calculates an ambient temperature of the measurement device based on measurement data of a second calibration gauge obtained by measuring a second calibration gauge made of a material different from the low thermal expansion material using the measurement device; and a temperature correction parameter determination unit that determines a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector, based on the ambient temperature calculated by the temperature calculation unit; and 7. The calibration device according to claim 5 or 6, comprising:

8. a temperature calculation unit that calculates an ambient temperature of the measurement device based on the measurement data of the first calibration gauge and the dimensions and thermal expansion coefficient of the calibration parameters at a reference temperature; a temperature correction parameter determination unit that determines a temperature correction parameter for correcting a detection error of at least one of the first detector and the second detector, based on the ambient temperature calculated by the temperature calculation unit; and 7. The calibration device according to claim 5 or 6, comprising:

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