JP2012207923A - Measuring instrument of scale for position detection, measurement method of scale for position detection, and method for manufacturing scale - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of detecting an error of a scale for position detection.SOLUTION: A measuring instrument of a scale for position detection includes a position detecting part which has a plurality of detecting parts for detecting position information of a scale used for position detection and is moved relatively in a movement direction with respect to the scale, and an error detecting part for detecting an error of the scale on the basis of detection results by at least two detecting parts among the plurality of detecting parts. The at least two detecting parts among the plurality of detecting parts are arranged at a predetermined first interval from each other in a movement direction.

Description

  The present invention relates to a position detecting scale measuring apparatus, a position detecting scale measuring method, and a scale manufacturing method.

  For position detection of a linear encoder or the like, a position detection scale having a pattern indicating position information is used. When measuring the error of the position detection scale, it is measured using a measuring device such as a laser interferometer (for example, see Non-Patent Document 1).

Seiji Sakamoto, Tetsuro Kiriyama, Motonori Sugawara, “High-resolution technology of linear encoder”, “Measurement and control”, Society of Instrument and Control Engineers, Vol. 44, No. 10, p. 662-667

By the way, in recent years, there has been a demand for minimizing fluctuations in errors that occur within a small section of the position detection scale. For example, an error of 0.1 μm at the maximum is allowed in a 100 mm section, but there is a demand to suppress the maximum error fluctuation in a small section (for example, 1 mm) to 1 nm or less.
However, it is difficult to measure a change of 1 nm with high reproducibility and high accuracy by a measuring apparatus such as the laser interferometer described above. That is, in the measuring apparatus such as the laser interferometer as described above, there is a problem that it is difficult to detect the error of the position detection scale with high accuracy.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a position detecting scale measuring apparatus and a position detecting scale measuring method capable of improving the accuracy of detecting an error in the position detecting scale. And providing a method for producing a scale.

  In order to solve the above problem, an embodiment of the present invention has a plurality of detection units that detect position information of a scale used for position detection, and moves relative to the scale in the movement direction. A position detection unit; and an error detection unit that detects an error of the scale based on a detection result of at least two of the plurality of detection units, and the at least two of the plurality of detection units. The two detecting units are arranged at predetermined first intervals in the moving direction, and are a position detecting scale measuring apparatus.

  In one embodiment of the present invention, a movement step of moving a position detection unit having at least two detection units for detecting position information of the scale relative to the scale in the movement direction, An error detection step of detecting an error of the scale based on detection results by the at least two detection units arranged at a predetermined first interval. .

  In addition, according to an embodiment of the present invention, a scale creating step for creating a scale used for position detection and an error of the scale are detected using the position detecting scale measuring apparatus according to the embodiment of the present invention. And an error detection step.

  According to the present invention, it is possible to improve the accuracy of detecting a scale error.

It is a schematic block diagram which shows the measuring device of the position detection scale by 1st Embodiment. It is a wave form diagram which shows an example of the measurement operation | movement of the measuring device of the position detection scale in 1st Embodiment. It is a flowchart which shows the measuring method of the scale for position detection in 1st Embodiment. It is a schematic block diagram which shows the measuring device of the position detection scale by 2nd Embodiment. It is a schematic block diagram which shows the measuring device of the position detection scale by 3rd Embodiment. It is a schematic block diagram which shows the measuring device of the position detection scale by 4th Embodiment. It is a schematic block diagram which shows the measuring device of the position detection scale by 5th Embodiment. It is a flowchart which shows the measuring method of the position detection scale in 5th Embodiment. It is a schematic block diagram which shows the scale manufacturing system by this embodiment. It is a flowchart which shows operation | movement of the scale manufacturing system in this embodiment.

  A position detecting scale measuring apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic block diagram showing a position detection scale measuring apparatus (hereinafter referred to as a scale measuring apparatus) according to the present embodiment.
In this figure, the scale measuring apparatus 1 includes a position detection unit 10, an error detection unit 20, and a moving unit 30. The scale measuring device 1 is connected to the control device 4 via a control signal line.
The scale measuring device 1 is attached with a position detection scale 3 (hereinafter referred to as a scale 3) to be measured. Here, the scale 3 is a scale used for position detection in a linear encoder, for example. The scale 3 has a pattern 31 indicating position information formed on the surface thereof. The pattern 31 is, for example, an incremental pattern.

The position detection unit 10 is disposed to face the scale 3, and moves relative to the scale 3 in the movement direction by the moving unit 30. Here, the moving direction is a direction in which position information is detected, and is the X-axis direction shown in FIG.
The position detection unit 10 includes a plurality of (two in the present embodiment) detection heads (11, 12) and a position information generation unit (13, 14).

The detection heads (detection units) (11, 12) are, for example, optical sensors, and detect the position information of the scale 3 by detecting the pattern 30 of the scale 3, and output a detection signal. The detection head 11 outputs a detection signal to the position information generation unit 13, and the detection head 12 outputs a detection signal to the position information generation unit 14.
Further, the detection heads (11, 12) are fixedly arranged at a predetermined interval L1 (first interval) in the moving direction. That is, the detection heads (11, 12) move relative to the scale 3 in the movement direction while maintaining the predetermined distance L1. For example, the predetermined interval L1 (first interval) in the present embodiment is desirably an interval that is not easily affected by environmental fluctuations such as temperature, and is about 10 mm.

The position information generation unit 13 is a counter that generates position information based on, for example, a detection signal detected by an incremental pattern. The position information generation unit 13 generates position information X1 on the scale 3 based on the detection signal output from the detection head 11, and outputs the generated position information X1 to the error detection unit 20 as a detection result.
The position information generation unit 14 is, for example, a counter that generates position information based on a detection signal detected by an incremental pattern. The position information generation unit 14 generates position information X2 on the scale 3 based on the detection signal output from the detection head 12, and outputs the generated position information X2 to the error detection unit 20 as a detection result.

  The error detector 20 detects an error of the scale 3 based on the detection results (X1, X2) by the two detection heads (11, 12). That is, the error detection unit 20 detects an error of the scale 3 based on the calculation result obtained by calculating the detection results (X1, X2) by the two detection heads (11, 12). In the present embodiment, as an example of arithmetic processing, the error detection unit 20 detects an error of the scale 3 based on a difference between detection results (X1, X2) by the two detection heads (11, 12). Will be explained.

  Here, the detection result X1 and the detection result X2 indicate position information detected by the detection head 11 and the detection head 12 when the position detection unit 10 is at the same position in the movement direction. That is, the detection head 11 and the detection head 12 are position information detected at a position apart from the predetermined interval L1 (first interval) described above on the scale 3.

  The error of the scale 3 is a difference between measured values with respect to the true value of the position information at each position of the scale 3 in the X-axis direction. Further, the error of the scale 3 includes an error caused by the production of the scale 3 (for example, connection of patterns (superposition) at the time of pattern formation), an error caused by a change over time due to use after production, and the like.

The error detection unit 20 outputs the detected error of the scale 3 to the control device 4. Further, the error detection unit 20 controls the moving unit 30 to move the position detecting unit 10.
The error detection unit 20 includes an error calculation unit 21 and a movement control unit 22.

  As described above, the error calculator 21 detects an error of the scale 3 based on the calculation result obtained by calculating the detection results (X1, X2) by the two detection heads (11, 12). The error calculation unit 21 includes a subtractor 211. The subtractor 211 executes a calculation process for calculating a difference D between the detection result X1 detected by the detection head 11 and the detection result X2 detected by the detection head 12. The difference D between the detection result X1 and the detection result X2 is a constant value indicating the predetermined interval L1 when the scale 3 is an ideal scale with no error. That is, the displacement of the difference D corresponds to the error of the scale 3. Therefore, the subtractor 211 outputs the difference D between the calculated detection result X1 and the detection result X2 to the control device 4 as an error of the scale 3.

  The movement control unit 22 controls the movement unit 30 to move the position detection unit 10. When measuring the error of the scale 3, the movement control unit 22 controls the moving unit 30 so that the position detecting unit 10 moves in the entire region from one end to the other end in the X-axis direction.

The control device 4 controls the error measurement of the scale 3 in the scale measuring device 1. The control device 4 supplies various measurement conditions such as a measurement start position and a measurement end position to the scale measurement device 1 via the control signal line. In addition, the control device 4 includes a maximum error calculation unit 41 and an inspection unit 42.
The maximum error calculation unit 41 calculates the maximum value of the error to be measured on the scale 3 based on the error (difference D) of the scale 3 calculated (detected) by the error calculation unit 21 of the error detection unit 20. Here, the error to be measured is, for example, an error in a small section or an error in a long section. The error in the small section is, for example, an error in the 1 mm section.
As an example, here, the maximum error calculation unit 41 calculates the difference ΔD between the maximum value and the minimum value in all the sections of the scale 3 as the maximum value of the error of the scale 3. However, the maximum error value (ΔD) of the scale 3 is twice the actual error, as will be described later. Therefore, a value obtained by halving the maximum error value (ΔD) of the scale 3 is used to determine whether the scale 3 is good or bad.

  The inspection unit 42 determines pass / fail of the scale 3 measured by the scale measurement device 1 based on the maximum error (ΔD) of the scale 3 calculated by the maximum error calculation unit 41. The inspection unit 42 determines the quality of the measured scale 3 based on, for example, a value obtained by halving the maximum error value (ΔD) of the scale 3.

Next, the operation of the scale measuring apparatus 1 in this embodiment will be described.
FIG. 2 is a waveform diagram showing an example of the measurement operation of the scale measuring apparatus 1 in the present embodiment.
In this figure, the horizontal axis indicates the position of the scale 3 in the X-axis direction. 2A shows the pattern 31 of the scale 3, and FIG. 2B shows the error of the scale 3 and the position of the position detector 10 at times T1 to T5. FIG. 2C shows an error (difference D) of the scale 3 detected by the scale measuring apparatus 1.

  As shown in FIG. 2A, the scale 3 shows an example in which there is an error in the positive direction from the position P2 to the position P4 on the X axis. Note that the pattern 31 of the scale 3 is formed, for example, by an exposure (photolithography) technique, and is formed by repeatedly forming a pattern having a predetermined section width. For example, the pattern 3 of the scale 3 is formed by overlay exposure or joint exposure of a pattern having a predetermined section width (for example, a width of a small section). In this example, a part of the repeated pattern (positions P2 to P4) is formed in a shifted manner.

First, the scale measuring apparatus 1 moves the position detection unit 10 in the X axis direction with respect to the scale 3. That is, the movement control unit 22 of the error detection unit 20 moves the position detection unit 10 in the X-axis direction from one end of the scale 3 to the other end with respect to the movement unit 30.
As shown in FIGS. 2B and 2C, at time T1, the position detection unit 10 has the detection head 11 at the position P1. In this case, since both the detection head 11 and the detection head 12 are positions where there is no error in the scale 3, the output (difference D) of the subtractor 211 of the error detection unit 20 is a constant value (predetermined interval L1). ) Is output.

  Next, at time T2, the position detection unit 10 has the detection head 11 at the position P3. In this case, the detection head 11 is located between the position P2 having an error and the position P4, and the detection head 12 is a position in a section having no error. For this reason, the output (difference D) of the subtractor 211 of the error detection unit 20 becomes a value larger than the fixed value (predetermined interval L1) by the error.

  Next, at time T3, the position detection unit 10 has the detection head 11 at the position P5. In this case, since both the detection head 11 and the detection head 12 are positions where there is no error in the scale 3, the output (difference D) of the subtractor 211 of the error detection unit 20 is a constant value (predetermined interval). A value indicating L1) is output.

  Next, at time T4, the position detection unit 10 has the detection head 11 at the position P6. In this case, the detection head 11 is in a position in a section having no error, and the detection head 12 is located between the position P2 and the position P4 having an error. For this reason, the output (difference D) of the subtractor 211 of the error detection unit 20 is a value smaller than the fixed value (predetermined interval L1) by the error.

  Next, at time T5, the position detection unit 10 has the detection head 11 at the position P7. In this case, since both the detection head 11 and the detection head 12 are positions where there is no error in the scale 3, the output (difference D) of the subtractor 211 of the error detection unit 20 is a constant value (predetermined interval). A value indicating L1) is output.

  In this way, the movement control unit 22 moves the position detection unit 10 in the X-axis direction from one end of the scale 3 to the other end with respect to the movement unit 30, so that the subtractor 211 is changed to FIG. A difference D between the detection result X1 by the detection head 11 and the detection result X2 by the detection head 12 is output. Further, the error of the scale 3 can be detected as a value obtained by halving the difference ΔD between the maximum value and the minimum value of the difference D.

Next, operations of the scale measuring device 1 and the control device 4 in the present embodiment will be described with reference to flowcharts.
FIG. 3 is a flowchart illustrating an example of the scale measurement method according to the present embodiment.
In this figure, first, the scale measuring apparatus 1 moves the position detector 10 from the measurement start position to the measurement end position (step S101). That is, the movement control unit 22 of the error detection unit 20 moves the position detection unit 10 from the measurement start position, which is one end of the scale 3, to the movement unit 30 based on the measurement conditions supplied from the control device 4. Move to a certain measurement end position. That is, the movement control unit 22 moves the position detection unit 10 relative to the scale 3 in the movement direction (X-axis direction). Then, while the position detection unit 10 is moved from the measurement start position to the measurement end position, the scale measuring apparatus 1 executes the processing from step S102 to step S105.

  Next, the position detection unit 10 detects the position information X1 and the position information X2 (step S102). That is, the position information generation unit 13 of the position detection unit 10 generates the position information X1 from the detection signal output from the detection head 11. Further, the position information generation unit 14 of the position detection unit 10 generates position information X2 from the detection signal output from the detection head 12.

  Next, the error detection unit 20 detects an error (difference D) of the scale 3 based on the position information X1 and the position information X2 (step S103). That is, the subtractor 211 of the error detection unit 20 calculates the difference D between the detection result (position information) X1 detected by the detection head 11 and the detection head 12 and the detection result X2. The subtractor 211 outputs the error of the scale 3 to the control device 4 (step S104).

  Next, the error detector 20 determines whether or not the position detector 10 is the measurement end position (step S105). If the error detection unit 20 determines that the position detection unit 10 is not at the measurement end position, the error detection unit 20 returns the process to step S102, and the process from step S102 to step S105 until the position detection unit 10 moves to the measurement end position. repeat. Further, the error detection unit 20 advances the process to step S106 when the position detection unit 10 is at the measurement end position.

  In step S106, the control device 4 calculates the maximum error ΔD. That is, the maximum error calculation unit 41 of the control device 4 calculates the maximum error ΔD of the scale 3 based on the error (difference D) of the scale 3 output from the subtractor 211 of the scale measuring device 1.

Next, the control device 4 determines the quality of the scale 3 (step S107). That is, the inspection unit 42 of the control device 4 determines whether or not the scale 3 measured by the scale measuring device 1 is a non-defective product based on the maximum error ΔD calculated by the maximum error calculating unit 41. Note that the criterion for determining whether or not the scale 3 is non-defective varies depending on the accuracy required for the scale 3, but is within ± 1 nm here, for example. The inspection unit 42 determines that the scale 3 is a non-defective product when the half value of the maximum error ΔD is 1 nm or less, and the scale 3 when the half value of the maximum error ΔD is greater than 1 nm. Is determined to be defective.
Thus, the process of this flowchart is completed.

  As described above, in the scale measuring apparatus 1 according to the present embodiment, the position detection unit 10 includes a plurality of detection heads (11, 12) that detect position information of the scale 3 used for position detection. Relative to the movement direction (X-axis direction). The error detection unit 20 detects an error of the scale 3 based on detection results (X1, X2) by at least two detection heads (11, 12) among the plurality of detection heads (11, 12). The at least two detection heads (11, 12) are arranged at a predetermined interval L1 (first interval) in the movement direction (X-axis direction).

That is, in the scale measuring apparatus 1 according to the present embodiment, the position detection unit 10 moves in a state where the predetermined interval L1 is maintained, and the detection result that is position information is obtained by at least two detection heads (11, 12). (X1, X2) is detected. Therefore, when the scale 3 is an ideal scale with no error, the detection result X1 and the detection result X2 are position information separated by a predetermined interval L1.
For example, when there is an error in the scale 3, the error in the scale 3 is detected as a displacement between the detection result X1 and the detection result X2. Note that the detection result X1 and the detection result X2 can be detected with high resolution in the same manner as the encoder using the scale 3. Therefore, the scale measuring device 1 in the present embodiment can improve the accuracy of detecting the error of the scale 3.

  For example, the position detection unit 10 can detect position information on the scale 3 in 1 nm units. Therefore, the scale measuring apparatus 1 in the present embodiment can detect an error in a small section in the scale 3 (for example, an error of 1 nm or less in a 1 mm section). That is, the scale measuring apparatus 1 in this embodiment can detect a local error (small section error) in the scale 3.

In the present embodiment, the error detection unit 20 detects an error of the scale 3 based on a difference (difference D) between detection results (X1, X2) by at least two detection heads (11, 12).
Thereby, the error of the scale 3 can be detected with high accuracy by a simple circuit configuration. Therefore, the scale measuring apparatus 1 in the present embodiment can improve the accuracy of detecting the error of the scale 3.

According to this embodiment, the measuring method of the scale 3 is such that the position detection unit 20 having at least two detection heads (11, 12) for detecting the position information of the scale 3 is relative to the scale 3 in the moving direction. Detection step (X1, X2) by the moving step (step S101 in FIG. 3) and the at least two detection heads (11, 12) arranged at a predetermined interval L1 (first interval) in the moving direction. And an error detection step (step S102 to step S105 in FIG. 3) for detecting an error of the scale 3.
Thereby, the measuring method of the scale 3 in this embodiment can improve the precision which detects the error of the scale 3. FIG.

[Second Embodiment]
Next, a scale measuring apparatus 1a according to the second embodiment will be described.
FIG. 4 is a schematic block diagram showing the scale measuring apparatus 1a according to the second embodiment.
The scale measuring device 1a in the present embodiment is different from the scale measuring device 1 in the first embodiment in that the filter processing unit 23 is provided, and the other configurations and operations are the scale measurement in the first embodiment. It is the same as the device 1.
In FIG. 4, the scale measuring device 1 a includes a position detection unit 10, an error detection unit 20 a, and a moving unit 30. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The error detection unit 20 a includes an error calculation unit 21, a movement control unit 22, and a filter processing unit 23.
The filter processing unit 23 is a high-pass filter that reduces the low-frequency component of the scale 3 error that is the output of the subtractor 211. That is, the filter processing unit 23 is, for example, a 1 mm spatial filter. The filter processing unit 23 reduces the low frequency component of the output of the subtractor 211 and passes the error component (high frequency component) in a small section (for example, 1 mm section). Thereby, the filter processing unit 23 makes it easy to detect an error in a small section (for example, a 1 mm section). The filter processing unit 23 outputs the filtered output of the subtracter 211 to the control device 4 as an error (difference D) of the scale 3.

  As described above, in the scale measurement apparatus 1a according to the present embodiment, the error detection unit 20a includes the filter processing unit 23 that reduces the low-frequency component of the scale 3 error, so that the scale 3 error in the small section is accurately detected. can do. Therefore, the scale measuring apparatus 1a in the present embodiment can improve the accuracy of detecting the error of the scale 3.

[Third Embodiment]
Next, a scale measuring apparatus 1b according to the third embodiment will be described.
In the first and second embodiments, the mode in which the difference by the subtractor 211 is applied as an example of the calculation process in the error calculation unit 21 has been described. However, in the present embodiment, another example of the calculation process is applied. Will be described.

FIG. 5 is a schematic block diagram showing a scale measuring apparatus 1b according to the third embodiment.
The scale measurement apparatus 1b in the present embodiment is the same as the scale measurement apparatus 1 in the first embodiment except that the configuration and operation of the error calculator 21b are different.
In FIG. 5, the scale measurement device 1 b includes a position detection unit 10, an error detection unit 20 b, and a movement unit 30. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The error detection unit 20 b includes an error calculation unit 21 b and a movement control unit 22.
The error calculation unit 21b executes a calculation of (dX2 / dX1) as an example of a calculation process for detecting an error of the scale 3 based on the detection results (X1, X2) by the detection heads (11, 12). Here, the detection results (X1, X2) include the reference detection result X1 and the target detection result X2. The reference detection result X1 is position information detected by the detection head 11 serving as a reference among the detection heads (11, 12). The target detection result X2 is position information detected by a detection head 12 different from the reference detection head 11 among the detection heads (11, 12).
In the present embodiment, as described above, the detection result (position information) X1 is represented as the reference detection result X1, and the detection result (position information) X2 is represented as the reference detection result X2.

  The error calculation unit 21b detects an error of the scale 3 based on the displacement amount (dX2 / dX1) by which the target detection result X2 is displaced when the reference detection result X1 is displaced by a predetermined amount. The error calculation unit 21b outputs the detected error of the scale 3 to the control device 4 as an output (difference D). The error calculation unit 21b includes a reference displacement amount detection unit 213, a position information latch unit 214, and a target displacement amount detection unit 215.

Based on the reference detection result X1 detected by the detection head 11, the reference displacement amount detection unit 213 outputs a trigger signal when the reference detection result X1 is displaced by a predetermined amount.
The position information latch unit 214 latches the position information, which is the target detection result X2 detected by the detection head 12, with the trigger signal output from the reference displacement amount detection unit 213, and detects the latched position information as the target displacement amount. To the unit 215.

  The target displacement amount detection unit 215 latches the position information output from the reference displacement amount detection unit 213 by the trigger signal output from the reference displacement amount detection unit 213, and then outputs from the reference displacement amount detection unit 213. The difference from the position information is calculated. That is, the target displacement detection unit 215 detects the displacement (dX2 / dX1) of the target detection result X2 when the reference detection result X1 is displaced by a predetermined amount.

  The displacement amount (dX2 / dX1) of the target detection result X2 is a constant value indicating a predetermined value when the scale 3 is an ideal scale with no error. That is, the displacement amount (dX2 / dX1) of the target detection result X2 corresponds to the error D of the scale 3. The target displacement detection unit 215 outputs the detected (calculated) displacement (dX2 / dX1) of the target detection result X2 to the control device 4 as the error D of the scale 3.

As described above, in the scale measurement device 1b according to the present embodiment, the error calculation unit 21b of the error detection unit 20b is displaced so that the target detection result X2 is displaced when the reference detection result X1 is displaced by a predetermined amount. Based on the quantity (dX2 / dX1), an error of scale 3 is detected.
Thereby, the error detection unit 20b can accurately detect the displacement between the detection result X1 (reference detection result) and the detection result X2 (target detection result). Therefore, the scale measuring device 1b in the present embodiment can improve the accuracy of detecting the error of the scale 3.

[Fourth Embodiment]
Next, a scale measuring apparatus 1c according to the fourth embodiment will be described.
In each of the first to third embodiments, the mode in which the position detection unit 10 includes two detection heads (11, 12) has been described. In the present embodiment, a mode in which three detection heads are provided will be described.

FIG. 6 is a schematic block diagram showing a scale measuring apparatus 1c according to the fourth embodiment.
The basic operation of the scale measuring apparatus 1c in this embodiment is the same as that of the scale measuring apparatus 1 in the first embodiment except that the number of detection heads is three.
In FIG. 6, the scale measuring device 1 c includes a position detection unit 10 c, an error detection unit 20 c, and a moving unit 30. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The position detection unit 10c includes three detection heads (11, 12, 15) and a position information generation unit (13, 14, 16). That is, the position detection unit 10c includes a detection head 11 (first detection unit), a detection head 12 (second detection unit), and a detection head 15 (third detection unit) as a plurality of detection heads. Yes.
Further, the first interval (predetermined interval L1) between the position where the detection head 11 is arranged and the position where the detection head 12 is arranged, the position where the detection head 12 is arranged, and the detection head 15 are The second interval (predetermined interval L2) between the arranged positions is different from each other. Further, the predetermined interval L1 (first interval) and the predetermined interval L2 (second interval) are not in multiples of each other. The detection head 11, the detection head 12, and the detection head 15 move relative to the scale 3 in the movement direction while maintaining the predetermined interval L1 and the predetermined interval L2.

  The detection head 15 (third detection unit) is, for example, an optical sensor similar to the detection head 11 and the detection head 12, and detects the position information of the scale 3 by detecting the pattern 30 of the scale 3. And outputs a detection signal. The detection head 15 outputs a detection signal to the position information generation unit 16.

  Similar to the position information generation unit 13 and the position information generation unit 14, the position information generation unit 16 is a counter that generates position information based on a detection signal detected by an incremental pattern, for example. The position information generation unit 16 generates position information X3 on the scale 3 based on the detection signal output from the detection head 15, and outputs the generated position information X3 as a detection result to the error detection unit 20c.

The error detection unit 20 c includes an error calculation unit 21 c and a movement control unit 22. The error calculation unit 21 c includes a subtractor 211 and a subtracter 212.
The subtractor 211 executes a calculation process for calculating a difference D1 between the detection result X1 detected by the detection head 11 and the detection result X2 detected by the detection head 12. The difference D1 between the detection result X1 and the detection result X2 is a constant value indicating the predetermined interval L1 when the scale 3 is an ideal scale with no error. That is, the displacement of the difference D1 corresponds to the error of the scale 3. Accordingly, the subtractor 211 outputs the difference D1 between the calculated detection result X1 and the detection result X2 to the control device 4 as an error of the scale 3.

  The subtractor 212 executes a calculation process for calculating a difference D2 between the detection result X2 detected by the detection head 12 and the detection result X3 detected by the detection head 15. The difference D2 between the detection result X2 and the detection result X3 is a constant value indicating the predetermined interval L2 when the scale 3 is an ideal scale with no error. That is, the displacement of the difference D2 corresponds to the error of the scale 3. Accordingly, the subtractor 212 outputs the difference D2 between the calculated detection result X2 and the detection result X3 as an error of the scale 3 to the control device 4.

In the present embodiment, the control device 4 determines the quality of the scale 3 based on the difference D1 between the detection result X1 and the detection result X2 and the difference D2 between the detection result X2 and the detection result X3.
Note that the error of the scale 3 may occur periodically at intervals close to the predetermined interval L1, for example. In such a case, an accurate error may not be detected with the error (difference D1) of the scale 3 detected at the predetermined interval L1. Therefore, in the present embodiment, the error (differences D1 and D2) of the scale 3 is detected based on different intervals between the predetermined interval L1 and the predetermined interval L2. Thereby, even in such a case, an accurate error can be detected from the error (difference D2) of the scale 3 detected by the predetermined interval L2 which is an interval different from the predetermined interval L1.

As described above, in the scale measuring apparatus 1c according to the present embodiment, the position detection unit 10c includes the detection head 11 (first detection unit), the detection head 12 (second detection unit), and a plurality of detection heads. A detection head 15 (third detection unit) is provided. Then, an interval (predetermined interval L1) between the position where the detection head 11 is arranged and the position where the detection head 12 is arranged, and the position where the detection head 12 is arranged and the detection head 15 are arranged. The interval 2 (predetermined interval L2) between the positions is different from each other.
Thereby, as described above, even when the error of the scale 3 is periodically generated by an interval close to the predetermined interval L1 or the predetermined interval L2, the error of the scale 3 can be accurately detected. Therefore, the scale measuring device 1c in the present embodiment can improve the accuracy of detecting the error of the scale 3.

[Fifth Embodiment]
Next, a scale measuring apparatus 1d according to a fifth embodiment will be described.
In the fourth embodiment, the mode in which the position detection unit 10c includes three detection heads has been described. In the present embodiment, the mode in which a plurality of position detection units 10 including two detection heads (11, 12) are provided is described. To do.

FIG. 7 is a schematic block diagram showing a scale measuring apparatus 1d according to the fifth embodiment.
The scale measurement apparatus 1d in the present embodiment is the same as the scale measurement apparatus 1 in the first embodiment except that the scale measurement apparatus 1d includes two position detection units 10.
In FIG. 7, the scale measuring device 1d includes two position detection units (10_1, 10_2), an error detection unit 20d, and a moving unit 30. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The position detection unit 10_1 (first position detection unit) includes detection heads (11_1, 12_1) and position information generation units (13_1, 14_1). The position detection unit 10_2 (second position detection unit) includes a detection head (11_2, 12_2) and a position information generation unit (13_2, 14_2). Note that the position detection unit 10_1 and the position detection unit 10_2 have the same configuration as the position detection unit 10 in FIG. That is, the detection head 11_1 and the detection head 11_2 correspond to the detection head 11, and the detection head 12_1 and the detection head 12_2 correspond to the detection head 12. In addition, the position information generation unit 13_1 and the position information generation unit 13_2 correspond to the position information generation unit 13, and the position information generation unit 14_1 and the position information generation unit 14_2 correspond to the position information generation unit 14.

  In the present embodiment, the detection head 11_1 and the detection head 12_1 are disposed at a predetermined interval L1 (first interval) in the movement direction. The detection head 11_2 and the detection head 12_2 are arranged at a predetermined interval L2 (second interval) in the moving direction. This predetermined interval L2 is an interval different from the predetermined interval L1 in the position detector 10_1. Further, the predetermined interval L1 and the predetermined interval L2 are not in a multiple relationship with each other. That is, the position detection unit 10_2 has at least two detection heads (11_2, 12_2) arranged at intervals different from the predetermined interval L1, and moves relative to the scale 3 in the movement direction.

  The position detection unit 10_1 outputs detection results (X1, X2) by the detection heads (11_1, 12_1) to the error detection unit 20d. Further, the position detection unit 10_2 outputs detection results (X3, X4) by the detection heads (11_2, 12_2) to the error detection unit 20d.

The error detection unit 20d includes an error calculation unit 21d and a movement control unit 22. The error calculator 21d includes a subtractor 211_1 and a subtractor 211_2.
The subtractor 211_1 and the subtractor 211_2 have the same configuration as the subtractor 211 in FIG. However, the subtractor 211_1 calculates a difference D1 between the detection result X1 detected by the detection head 11_1 and the detection result X2 detected by the detection head 12_1, and outputs the difference D1 to the control device 4 as an error of the scale 3. The subtractor 211_2 calculates a difference D2 between the detection result X3 detected by the detection head 11_2 and the detection result X4 detected by the detection head 12_2, and outputs the difference D2 to the control device 4 as an error of the scale 3.

Next, the scale measuring apparatus 1d in this embodiment will be described.
FIG. 8 is a flowchart showing the operation of the scale measuring apparatus 1d in the present embodiment.
In this figure, first, the scale measuring apparatus 1d measures (detects) an error (difference D1) of the scale 3 by the position detection unit 10_1 (step S201). The processing in step S201 is the same as the processing from step S101 to step S105 in FIG. The error detection unit 20d outputs the calculated error (difference D1) of the scale 3 to the control device 4.

  Next, the scale measuring device 1d measures (detects) the error (difference D2) of the scale 3 by the position detection unit 10_2 (step S202). In other words, the scale measuring device 1d switches from the position detection unit 10_1 to the position detection unit 10_2 and measures (detects) the error (difference D2) of the scale 3 in the same manner as the position detection unit 10_1. The error detection unit 20d outputs the calculated error (difference D2) of the scale 3 to the control device 4.

  Next, the control device 4 calculates maximum errors ΔD1 and ΔD2 (step S203). That is, the maximum error calculation unit 41 of the control device 4 calculates the maximum errors ΔD1 and ΔD2 of the scale 3 based on the errors (differences D1 and D2) of the scale 3 output from the error detection unit 20d of the scale measurement device 1. To do.

Next, the control device 4 determines the quality of the scale 3 (step S204). That is, the inspection unit 42 of the control device 4 determines whether or not the scale 3 measured by the scale measuring device 1 is a non-defective product based on the maximum errors ΔD1 and D2 calculated by the maximum error calculation unit 41.
Thus, the process of this flowchart is completed.

  Note that the error of the scale 3 may occur periodically at intervals close to the predetermined interval L1, for example. In such a case, an accurate error may not be detected with the error (difference D1) of the scale 3 detected at the predetermined interval L1. Therefore, in the present embodiment, the error (differences D1 and D2) of the scale 3 is detected twice based on different intervals between the predetermined interval L1 and the predetermined interval L2. Thereby, even in such a case, an accurate error can be detected from the error (difference D2) of the scale 3 detected by the predetermined interval L2 which is an interval different from the predetermined interval L1.

  As described above, the scale measuring device 1d according to the present embodiment includes the position detection unit 10_1 (first position detection unit) and the position detection unit 10_2 (second position detection unit). The position detection unit 10_1 has at least two detection heads (11_1, 12_1) arranged at a predetermined interval L1 (first interval), and moves relative to the scale 3 in the movement direction. The position detection unit 10_2 (second position detection unit) includes at least two detection heads (11_2, 12_2) arranged at a predetermined interval L2 (second interval) different from the predetermined interval L1. It moves relative to the scale 3 in the moving direction. The error detection unit 20d detects an error of the scale 3 based on the detection results obtained from the position detection unit 10_1 and the position detection unit 10_2.

  Thereby, as described above, even when the error of the scale 3 is periodically generated by an interval close to the predetermined interval L1 or the predetermined interval L2, the error of the scale 3 can be accurately detected. Therefore, the scale measuring device 1d in the present embodiment can improve the accuracy of detecting the error of the scale 3.

Further, according to the present embodiment, the measuring method of the scale 3 includes a plurality of position detection units (10_1, 10_2) having at least two detection heads arranged at different intervals of the predetermined interval L1 and the predetermined interval L2. And a step of detecting an error of scale 3 (step S201 and step S202 in FIG. 8).
Thereby, as described above, even when the error of the scale 3 is periodically generated by an interval close to the predetermined interval L1 or the predetermined interval L2, the error of the scale 3 can be accurately detected.

[Sixth Embodiment]
The scale measuring devices (1, 1a, 1b, 1c, 1d) in the first to fifth embodiments described above can be applied to a scale manufacturing system and a scale manufacturing method. In this embodiment, as an example, a scale manufacturing system including the scale measuring device 1 in the first embodiment will be described.

FIG. 9 is a schematic block diagram showing the scale manufacturing system 100 according to the present embodiment.
In this figure, the scale manufacturing system 100 includes a scale measuring device 1, a scale creating device 2, and a control device 4.

  The scale creation device 2 is a device that creates the scale 3. For example, the scale creation device 2 forms a pattern 31 that forms position information on the scale 3 by an exposure (photolithography) technique. The scale creation device 2 creates the pattern 31 by repeatedly forming a pattern having a predetermined section width. The scale creating process of the scale creating apparatus 2 includes a pattern forming process for forming position information on the scale 3.

The control device 4 controls each device of the scale manufacturing system 100. The control device 4 includes a maximum error calculation unit 41, an inspection unit 42, and a storage unit 43.
The storage unit 43 stores the creation conditions of the scale creation device 2, the measurement conditions of the scale measurement device 1, the error (error information) of the scale 3 detected by the scale measurement device 1, and the like.
The inspection unit 42 determines the quality of the scale 3 measured by the scale measuring device 1 based on the maximum value of the error of the scale 3 calculated by the maximum error calculation unit 41. In addition, when the measured scale 3 is a defective product, the inspection unit 42 analyzes the error information of the scale 3 measured (detected) by the scale measuring device 1 and can change the creation conditions of the scale 3. It is determined whether or not there is. When it is determined that the scale 3 creation condition tends to be changed, the inspection unit 42 changes the scale 3 creation condition in the scale creation device 2.

FIG. 10 is a flowchart showing the operation of the scale manufacturing system 100 in the present embodiment.
In this figure, first, the scale creation device 2 creates a scale 3 used for position detection (step S301). That is, the scale creation device 2 creates the scale 3 based on the creation conditions supplied from the control device 4. Note that the processing in step S301 corresponds to the scale creation process and includes a pattern formation process for forming position information on the scale 3 as described above.

  Next, the scale manufacturing system 100 measures (detects) an error of the scale 3 using the scale measuring device 1 (step S302). That is, the scale measuring device 1 detects an error of the scale 3 based on the control of the control device 4. Note that the error of the scale 3 measured by the scale measuring device 1 is stored in the storage unit 43 of the control device 4.

  Next, the scale manufacturing system 100 inspects the scale 3 based on the measurement result of the scale measuring device 1 (step S303). That is, the maximum error calculation unit 41 of the control device 4 calculates the maximum error ΔD of the scale 3 based on the error (difference D) of the scale 3 output from the scale measurement device 1. The inspection unit 42 inspects the scale 3 based on the maximum error ΔD calculated by the maximum error calculation unit 41.

  Next, the scale manufacturing system 100 determines whether or not the scale 3 is a non-defective product (step S304). That is, the inspection unit 42 determines whether or not the scale 3 is a non-defective product based on the maximum error ΔD calculated by the maximum error calculation unit 41. If the scale 3 is a non-defective product, the inspection unit 42 ends the process. The inspection unit 42 advances the process to step S305 when the scale 3 is defective.

  In step S <b> 305, the scale manufacturing system 100 analyzes the error information of the scale 3. In other words, the inspection unit 42 performs measurement with the scale measuring apparatus 1 so far, reads out and analyzes the error of the scale 3 stored in the storage unit 43. Note that the error of the scale 3 used for this analysis may be error information measured by a plurality of scales 3.

  Next, the inspection unit 42 determines whether there is a tendency to change the creation condition of the scale 3 based on the above analysis result (step S306). If the inspection unit 42 determines that there is a tendency to change the creation condition, the processing proceeds to step S307. If the inspection unit 42 determines that there is no tendency to change the creation condition, the processing ends.

  In step S307, the inspection unit 42 changes the creation condition of the scale 3 stored in the storage unit 43, and returns the process to the next scale creation step (step S301). Thereby, in the next scale creation process, scale 3 is created based on the changed creation conditions.

  Here, the tendency that the creation condition of the scale 3 can be changed is, for example, a case where a plurality of scales 3 have large errors at the same position. In this case, it is conceivable that the alignment conditions for forming the pattern 31 at the position where the error of the scale 3 is large are not appropriate. Therefore, the error of the scale 3 can be reduced by changing the alignment condition when forming the pattern 31 at the position where the error of the scale 3 is large.

As described above, the scale manufacturing system 100 according to the present embodiment includes the scale creation device 2 that creates the scale 3 used for position detection and the scale measurement device 1.
Since the accuracy of detecting the error of the scale 3 can be improved by the scale measuring device 1, the scale manufacturing system 100 in the present embodiment can manufacture the scale 3 with reduced error.

Further, the scale manufacturing system 100 according to the present embodiment changes the creation conditions of the scale 3 in the scale creation device 2 based on the error of the scale 3 detected by the scale measurement device 1.
Thereby, since the scale creation apparatus 2 creates the scale 3 under appropriate creation conditions, the error of the scale 3 can be reduced. Therefore, the scale manufacturing system 100 in this embodiment can manufacture the scale 3 with reduced errors.

According to the present embodiment, the scale 3 manufacturing method includes a scale creation step (step S301 in FIG. 10) for creating the scale 3 used for position detection, and an error of the scale 3 using the scale measurement device 1. And an error detection step (step S302 in FIG. 10).
Thereby, the manufacturing method of the scale 3 by this embodiment can manufacture the scale 3 which reduced the error.

Further, the scale 3 manufacturing method according to the present embodiment changes the scale creation conditions in the scale creation step based on the error of the scale 3 detected by the error detection step.
Thereby, since the scale creation process creates the scale 3 under appropriate creation conditions, the error of the scale 3 can be reduced. Therefore, the manufacturing method of the scale 3 in this embodiment can manufacture the scale 3 with reduced errors.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
In each of the above embodiments, the mode in which the position detection unit 10 (10c) includes the position information generation units 13 and 14 (13, 14, and 16) has been described. However, the error detection unit 20 (20c) has the position information generation unit. 13 and 14 (13, 14, and 16) may be included. Alternatively, the detection heads 11 and 12 (11, 12, and 15) of the position detection unit 10 (10c) may move relative to the scale 3 in the movement direction.

  Moreover, although said 1st-5th each embodiment demonstrated as a form implemented individually, respectively, the form implemented combining the 1st-5th each embodiment may be sufficient. For example, the filter processing unit 23 of the second embodiment may be applied to the third to fifth embodiments. In addition, the first, second, fourth, and fifth embodiments include the error calculation unit 21b (21a, 21c) including the error calculation unit 21b of the third embodiment and the subtraction circuit 211 (212, 211_1, 211_2). , 21d).

Moreover, in said 6th Embodiment, although the scale manufacturing system 100 and the manufacturing method of the scale 3 demonstrated the form which uses the scale measuring device 1 by 1st Embodiment as an example, from 2nd, The form which uses scale measuring device 1a (1b, 1c, 1d) by each 5th embodiment may be sufficient.
Further, in the above sixth embodiment, the form in which the scale measuring device 1 is used as the measuring device for manufacturing the scale 3 has been described. However, when the scale 3 is evaluated in the calibration of the encoder, the scale measuring device is used. 1 (1b, 1c, 1d) may be used.

  Further, in each of the embodiments described above, the scale 3 has the form having the incremental pattern as the pattern 31, but the form having the absolute pattern may be used, and the form having other patterns as long as the position information can be detected. Good. For example, the scale 3 may have a form having both an incremental pattern and an absolute pattern. The detection heads (11, 12, 15) are not limited to optical sensors, but may be magnetic sensors.

Further, in each of the embodiments described above, the scale 3 is a linear encoder scale. However, the scale 3 may be applied to a disk-type scale or a fan-shaped scale used for a rotary encoder.
In each of the above embodiments, the moving unit 30 has been described as moving the position detecting unit 10 (10c). However, the moving unit 30 may be configured to move the scale 3.

  Further, in each of the above embodiments, the maximum error calculation unit 41 has been described as calculating the difference ΔD between the maximum value and the minimum value of the error (difference D) of the scale 3 as the maximum value of the error of the scale 3. However, the present invention is not limited to this. For example, the maximum error calculation unit 41 may calculate a value obtained by halving the difference ΔD as the maximum error of the scale 3. Further, the maximum error calculation unit 41 may be configured to calculate the difference ΔD between the maximum value and the minimum value in the value obtained by moving and averaging the error (difference D) of the scale 3.

  1, 1a, 1b, 1c, 1d ... scale measuring device, 10, 10c, 10_1, 10_2 ... position detection unit, 11, 12, 11_1, 11_2, 12_1, 12_2, 15 ... detection head, 20, 20a, 20b, 20c , 20d ... error detection unit, 23 ... filter processing unit

Claims (10)

A plurality of detection units for detecting position information of a scale used for position detection, and a position detection unit that moves relative to the scale in a movement direction;
An error detection unit that detects an error of the scale based on detection results of at least two of the plurality of detection units,
The at least two detection units of the plurality of detection units are arranged at a predetermined first interval in the movement direction. The position detection scale measuring apparatus. The error detector is
The position measuring scale measuring apparatus according to claim 1, wherein the scale error is detected based on a difference between detection results of the at least two detection units. The detection result includes a reference detection result detected by the detection unit serving as a reference of the detection units and a target detected by the detection unit different from the detection unit serving as the reference of the detection units. Detection results and
The error detector is
3. The scale error is detected based on a displacement amount by which the target detection result is displaced when the reference detection result is displaced by a predetermined amount. 4. Measuring device for scale for position detection. The error detector is
The position measuring scale measuring apparatus according to any one of claims 1 to 3, further comprising a filter processing unit that reduces a low-frequency component of the scale error. The position detector is
As the plurality of detection units, a first detection unit, a second detection unit, and a third detection unit,
The first interval between the position where the first detection unit is arranged and the position where the second detection unit is arranged, the position where the second detection unit is arranged, and the first 5. The position of the position detection scale according to claim 1, wherein the second distance between the position where the three detection units are arranged is different from each other. Measuring device. Having at least two detection units arranged at intervals different from the first interval, and having a second position detection unit that moves relative to the scale in the movement direction;
6. The error detection unit detects an error of the scale based on detection results obtained from the position detection unit and the second position detection unit. 6. The position detecting scale measuring device according to claim 1. A movement step of moving a position detection unit having at least two detection units for detecting position information of the scale relative to the scale in the movement direction;
An error detection step of detecting an error of the scale based on detection results by the at least two detection units arranged at predetermined first intervals in the movement direction;
A method for measuring a position detecting scale, comprising: A scale creation process to create a scale used for position detection;
An error detecting step of detecting an error of the scale using the position detecting scale measuring device according to any one of claims 1 to 6;
A method for producing a scale, comprising: The scale production method according to claim 8, wherein the scale creation conditions in the scale creation step are changed based on the scale error detected by the error detection step. The scale production method according to claim 8 or 9, wherein the scale creation step includes a pattern formation step of forming position information on the scale.

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