KR101055639B1 - Measuring system - Google Patents

Abstract

PURPOSE: A measuring system which can obtain the high precision of measurement is provided improve high precision of measurement and reduce costs for composing the device. CONSTITUTION: A measuring system comprises a reference ruler(110), a light focusing member(120), and a light measuring member(130). The reference ruler comprises includes scale parts, which is alternately located, and includes a recessed part and a protruding part. The light focusing member emits light to reference ruler and collects the light reflected from the reference ruler.

Description

Measuring System {Measuring System}

The present invention relates to a measurement system.

In order to enable the various machines for factory automation to locate and move the correct position, a linear scale is required along with sensors and controllers. The type of linear used generally is shown in FIG. 1. As shown, in the case of a general conventional linear ruler, the scales are formed at regular intervals so that the fixed reference ruler 1 is installed, and the comparator 2, which is also scaled at regular intervals, is provided side by side. The light emitted from the light source 3 is reflected by the reflector 4 to sequentially pass through the comparator 2 and the reference 1. When the light emitted through the comparator 2 and the reference 1 is sequentially measured, a beat phenomenon occurs according to the degree of deviation of the scales of the comparator 2 and the reference 1. This causes a change in the amount of light. The amount of light of the measurement light generally forms a sine wave, which receives a signal having a 90 ° retardation (that is, forms a cosine wave) from the measurement light and simultaneously uses the signal, thereby moving the signal. It can also be measured. According to this principle, the feeder (of an automatically operated machine) arrives at the desired position using the pitch of the scale engraved on the reference 1 and the comparator 2, the change in the amount of light of the measurement light, and the like. It can be confirmed by calculating whether or not.

On the other hand, in order to be able to move the conveying part of the automatically operated machine to the correct position, it is natural that the origin setting must be made. At this time, the operation is not stopped when the feeder returns to the origin during machine operation. In general, the operation is usually stopped when it is in an arbitrary position, and therefore the home setting should always be made at the beginning of operation. To this end, the reference point 1 and the comparator 2 are further formed with reference points (1a) (2a) that can be used to set the origin.

However, in order to enable the linear ruler as described above to operate correctly, the scale should be precisely and accurately formed on the standard 1 and the comparator 2, and thus the standard 1 and the The manufacturing of the comparator 2 is expensive.

On the other hand, in a data pickup device for reading data from a data storage medium (hereinafter, referred to as an optical disc) using optical such as CD and DVD, a control is required to read a track of the optical disc without missing it. As shown in Fig. 2A, continuous digital data is arranged in a spiral form on the optical disk surface. At this time, it is natural that not only the data center but also the center of the circle formed by the optical disc is formed. As the optical disk rotates, the data pickup device irradiates light onto the surface of the optical disk, measures the reflected light, and reads the data through the optical disk. It's physically very difficult. That is, in actual use, the optical disc rotates with the rotational center and the data center displaced as shown in (partly exaggerated) in Fig. 2 (B), so that the data pickup device is engraved on the optical disc without error while following one track. In order to read digital data, that is, not to miss a track that has been followed (called an on-track), the data pickup device moves left and right according to the movement of the optical disc.

In such a data pickup device, various methods are used as a tracking method for controlling the movement so as not to deviate from the track being read. Among them, a three-beam method, a push-pull method, and a DPD method are representative.

By the way, the purpose of the tracking method in the optical disk data pickup device is to follow one track without missing it, so that the control is performed within a range where a slight error occurs to the left and right of the track. In other words, in the tracking method of the optical disc data pickup apparatus, when a position is changed to follow another track but completely follows the track following by an external shock or the like, and is changed to match another track, the track that has been adjusted at the changed position is newly refreshed. It's well known that you can't find out how many locations were skipped, where they were before they were skipped, and so on. (In order to solve this problem, a read ahead method using a buffer is applied and used, which is completely separate from the tracking method.)

Accordingly, the present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to apply a tracking method used in an optical disk pickup device, and the cost of device construction is relatively low, but high measurement accuracy is achieved. To provide a measurement system that can be obtained.

The measurement system of the present invention for achieving the above object, the reference member 110 including a graduation portion 110A formed with recesses and convex portions alternately arranged at regular intervals; Light focusing means (120) for irradiating incident light onto the reference (110) and focusing and outputting the reflected light reflected from the reference (110); Laser light source 131 for injecting light into the light focusing means 120 so that the incident light is irradiated to the reference ruler 110 by the light focusing means 120, the reflected light focused from the light focusing means 120 The optical measuring means 130 includes a plurality of photodiodes 132 for measuring the incident light and a calculation unit 133 for calculating position information using at least one pair of optical signals measured by the photodiodes 132. ); The light measuring means 130 applies a tracking method when the relative position is moved between the reference member 110 and the light focusing means 120, but the photodiode 132 may include the at least one. Measuring the pair of optical signals, and using the magnitude and phase difference of each of the measured at least one pair of optical signal values, measuring the number of graduations and the moving direction passed by the scale unit 110A according to the position movement size, It is characterized by calculating the moving distance and the direction using this.

In this case, the light measuring means 130 is characterized by using any one of the tracking method selected from the three-beam method, push-pull method (difference phase detection) method.

At this time, the light measuring means 130 uses a three-beam method, wherein the light measuring means 130 is the primary beam (0th order light and 0th order light) emitted from the laser light source 131 And a hologram for separating and forming a pair of sub-beams, which are formed to the left and right of the first beam, and having a magnitude and a phase difference of the optical signals of the pair of sub-beams reflected from the reference 110. By using, it is characterized in that for measuring the number of scales and the moving direction passed by the scale unit 110A according to the position movement size. In this case, the optical measuring means 130, the pitch p of the scale formed in the scale portion 110A, and the distance d between the pair of sub-beams in a direction parallel to the scale interval direction is expressed by the following equation. Forming a relationship.

d = k * p ± p / 4 (an integer where k = 0, 1, 2,…)

In this case, the optical measuring unit 130 may rotate the hologram to adjust the distance d between the pair of subbeams.

Alternatively, the light measuring means 130 uses a push-pull method, wherein the light measuring means 130 emits light of a single spot by the laser light source 131, and the photodiode 132 is composed of a two-division element, using the magnitude and phase difference of the pair of optical signals measured from the two sides of the light reflected from the reference 110, the scale unit 110A according to the position movement size It is characterized by measuring the number of scales and the moving direction in the).

Alternatively, the optical measuring means 130 uses a DPD method, wherein the optical measuring means 130 emits light of a single spot by the laser light source 131, and the photodiode 132. Consists of a four-division element, and the position shift size by using the magnitude and phase difference of the pair of optical signals consisting of the sum of the optical signals in a pair of diagonal directions of the light reflected from the reference 110 In accordance with it characterized in that the number of scales and the direction of movement passed by the scale portion (110A) is measured.

In addition, the reference ruler 110 is formed of a transparent material that transmits light, and the transparent material 111 is formed of a transparent material 111 having irregularities at the position of the scale portion 110A on one side and the transparent material 111 as a material reflecting light. It is characterized by consisting of a reflector 112 is coated on the side of the uneven surface formed.

According to the present invention, by applying the principle of the optical disk data pickup device that can be mass-produced at a low price, there is an effect to replace the linear ruler for position measurement provided in the transfer unit of the automated machine. That is, by replacing the linear device, which is produced at a very high cost by the manufacture of precision, with the device of the present invention, the position measurement can be performed accurately and accurately, and there is a great economic effect that can make the cost of the equipment much lower. .

In particular, the apparatus of the present invention has the advantage that it can be optimally applied to the micro stage where the stroke of the conveying unit is relatively small, that is, precise fine work is performed.

1 is a conventional linear ruler.
2 is a conventional optical disk data pickup device principle.
3 is a measurement system of the present invention.
4 is a measurement principle using a three-beam method.
5 is a sub-beam signal shape according to the phase difference when measuring using the three-beam method.
6 is a measurement principle using a push-pull method.
7 is a measurement principle using the DPD method.

Hereinafter, a measuring system according to the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings.

3 shows a schematic configuration of the measuring system of the present invention. As shown, the measuring system of the present invention includes a reference 110, a light focusing means 120, and a light measuring means 130. Hereinafter, each part will be described in more detail.

As shown in FIG. 1, the reference ruler 110 includes a graduated portion 110A having recesses and convex portions alternately arranged at regular intervals. In this case, the reference ruler 110 is formed of a transparent material that transmits light, and the transparent material 111 is formed of a transparent material 111 having irregularities formed at the position of the scale part 110A on one side and the transparent material ( It is preferable that the reflector 112 is coated on the uneven surface forming side of the 111. Accordingly, when light is incident from the outside to the scale portion 110A, the light intensity of the optical signal reflected by the irregularities of the scale portion 110A is changed.

The light converging means 120 irradiates incident light to the reference ruler 110 and focuses and outputs the reflected light reflected from the reference ruler 110. That is, the light converging means 120 plays a role of injecting light into the reference 110 and serves to focus and output the light reflected from the reference 110. In FIG. 3, the light converging means 120 is briefly shown to include a reflector for changing the direction of light, a collimator lens for making incident light into parallel light, and an objective lens for collecting the incident parallel light at a focal position. However, this is only one example of the light converging means 120, and thus, the present invention is not limited thereto. In addition, the present invention may further include various components such as a polarizing plate, or at least not shown in FIG. 3. It may also be in other forms. In other words, the light converging means 120 may inject light into the reference ruler 110, and in some form, the light converging means 120 may focus and output the reflected light reflected from the reference ruler 110. It may be done.

The light measuring means 130 is a laser light source 131 for injecting light into the light focusing means 120 so that the incident light is irradiated to the reference 110 by the light focusing means 120, the light focusing A plurality of photodiodes 132 that receive and measure the reflected light focused from the means 120, and a calculation unit 133 that calculates position information using at least one pair of optical signals measured by the photodiodes 132. It is made, including. That is, the light measuring means 130 emits incident light to be radiated to the reference ruler 110, and also serves to measure the reflected light reflected from the reference ruler 110.

The reference ruler 110 and the light focusing means 120 are moved relative to each other. At this time, if it is possible to surely determine how many scales of the reference ruler 110 has passed, the reference ruler 110 and The relative position movement distance between the light focusing means 120 can be obtained with high accuracy as much as (or more) than the graduation interval. That is, in the case of the measuring system of the present invention, it can be used for a mechanical device that is controlled automatically, etc., the reference member 110 is provided on a fixed part and the light focusing means 120 may be provided on the moving part, Or vice versa, or if only relative position is important, both may be provided in the moving parts. Here, the light focusing means 120 and the light measuring means 130 may be integrally formed, or the laser light source 131 and the photodiode 132 in the light measuring means 130 may be It is formed integrally with the light converging means 120, the calculation unit 133 may be provided in a separate position, the shape is changed in various ways depending on the design purpose or intention, the characteristics of the device provided, etc. The above description is only a few examples and thus the present invention is not limited thereto.

In the case of the conventional linear ruler shown in FIG. 1, two rulers were required, a reference and a comparator. However, in the present invention, since only one reference ruler is required, the configuration of the conventional linear ruler may be much simpler than the conventional linear ruler. In addition, the present invention is characterized in that the tracking method used in the data pickup device of the optical disc is used to measure the number of tick marks and the moving direction in the reference ruler 110 (when the relative position moves). That is, in the present invention, when the relative position movement between the reference 110 and the light focusing means 120, the light measuring means 130 applies a tracking method, the photodiode 132 in the at least one pair The optical signals of the optical signals are measured, and by using the magnitudes and phase differences of the measured at least one pair of optical signal values, the number of graduations and the moving direction of the scales passed by the scale unit 110A are measured according to the size of the position movement. To calculate travel distance and direction.

On the other hand, the tracking method used in the data pickup device of the optical disk, such as a three-beam method, a push-pull method, a difference phase detection (DPD) method, and the like as briefly described above. This method itself is already widely commercialized and well known, but its orientation is completely different for application to the measurement system as in the present invention. This is briefly described below.

As shown in Fig. 2 (A), the optical disc has a shape in which one track is spirally arranged on a circular substrate. It is important whether or not the pick-up device follows a track completely when picking up data on such an optical disc. Accordingly, various tracking methods as described above have been used. In the tracking method of the optical disk data pickup apparatus, when there is a predetermined position change around one track, it is controlled. In other words, if it is detected that the track position is slightly shifted during data pickup, centering on the track being tracked (called on-track), it is moved to the position out of the pickup device and adjusted again. Note was controlled in such a way. In other words, in the case of the conventional tracking method, the position fluctuation range is less than the distance between tracks, and thus the control method is also designed within this range.

Therefore, in the case of controlling by the tracking method in the conventional optical disk pickup apparatus, when the position is greatly shaken due to an external impact or the like and skipped to the wrong position at all, the data pickup is held by catching the track nearest the skipped position as a new on-track. Will be done. At this time, the control by the tracking method that has been conventionally applied is a method of returning to the correct track position when the position variation width is less than the distance between the tracks as described above. Tasks such as calculating the distance between moved on-tracks could not be performed. (Of course, a technique such as using a buffer to solve the track jumping problem caused by an external impact is introduced, but this technique is completely independent of the tracking.) In other words, the conventional tracking method allows a track to be completely followed. There was no consideration of skipping tracks.

However, in the present invention, the principles of the tracking method are applied as they are, but each track is regarded as a separate track, and the position is moved by using the reflected light reflected from the scale 110A of the reference ruler 110. As a result, the distance and direction of the moved position are calculated by measuring how many scales are passed and in which direction. That is, in the present invention, in measuring the number of scales and the moving direction in the optical measuring means 130, any one selected from the three-beam method, push-pull method, difference phase detection (DPD) method A tracking method is applied, and the photodiode 132 measures the at least one pair of optical signals, and uses the magnitude and phase difference of the measured values of the at least one pair of optical signals, and a principle thereof. Is shared, but the purpose and scope of application of the principles of the present invention and the conventional data pickup device is made at all different.

Hereinafter, the three-beam method, the push-pull method, and the DPD method will be described in more detail with respect to the principle of measuring the number of ticks and the direction of movement in accordance with the position movement size in the present invention.

(1) 3-beam system

The case where the light measuring means 130 uses a three-beam method will be described.

When using the three-beam method, the light measuring means 130 is a pair of sub-beams formed by the light emitted from the laser light source 131 to the left and right of the 0-order light and the 0-order light of the main beam It further comprises a hologram (not shown) to separate the formed into ± ± 1 st light, and using the size and phase difference of the optical signal of the pair of sub-beams reflected from the reference 110, according to the position shift size The number of scales and the moving direction passed by the scale unit 110A are measured.

This will be described in more detail with reference to FIG. 4. In the three-beam system, when the laser light emitted from the laser light source 131 passes through a hologram such as a diffraction grating, 0-order light, ± 1-order light, ± 2-order light, ... This will be made. At this time, the light of ± 2 orders of magnitude or more is inadequate for practical use in measurement, since its intensity is very weak. Accordingly, 0th order light is used as the main beam and ± 1st order light as a pair of subbeams.

4 (A) shows various forms in which three beams are irradiated to a track or scale according to the position. In the center view of FIG. 4 (A), the main beam is accurately positioned on the track or scale, and a pair of subbeams are tracked. The case where it is located in the reflecting part of right and left is shown. The left view of FIG. 4A shows the case where the main beam is biased to one side of the track or scale, and the right view of FIG. 4A shows the case where the main beam is biased to the opposite side.

 FIG. 4B shows an example of a signal obtained for tracking in the data pickup apparatus using three beams, which will be described in more detail with reference to FIG. 4A. In the data pickup apparatus, the main beam reads track information and performs tracking by a pair of subbeams, as shown in FIG. 4 (B), where the first subbeam and the second subbeam ( The difference value between 2nd sub beams is measured and used as a tracking signal. Since the beam irradiated to the position other than the track is mostly reflected, the light intensity is large. In the left view of Fig. 4A, the first subbeam is about halfway across the track so that the light intensity of the reflected light is reduced by half, and since the second subbeam is at the reflector position, the light intensity of the reflected light is maximum. Therefore, the tracking signal S value obtained by (first subbeam light intensity-second subbeam light intensity) has a value indicated by 1 in FIG. 4 (B). In the center view of FIG. 4A, the main beam is accurately positioned on the track, and the positions of the first subbeam and the second subbeam are the same with respect to the track position, and the reflected light intensity of each of the first subbeam and the second subbeam is The same appears and thus has a zero value, indicated by 2 in FIG. 4 (B). In the case of the right side of FIG. 4A, the reverse view of the left side of FIG. 4A may be considered. Therefore, in this case, the tracking signal S value has a value indicated by 3 in FIG. 4B. This tracking signal S value is in the form of a periodic function such as a sine wave as shown in FIG. 4 (B).

In the case of the data pickup device, the purpose of this tracking signal value is 0. Therefore, if a non-zero value such as S value 1 or 3 is shown in Fig. 4 (B), the data pickup is performed so that the S value is 0. Control to move the position of the device is performed. Considering this process, the tracking signal in the data pickup device can be effectively used only when the measurement signal is measured at a period within the period of sine wave, especially the maximum range from -1/2 cycle to +1/2 cycle. It can be seen. If this range is exceeded, there is a risk of skipping the track, so that the actual change of the tracking signal in the position control of the data pickup device is only made near the origin.

4 (C) shows an example of device configuration and an example of a signal obtained at the time of applying the three-beam method in the measurement system of the present invention. In the data pickup apparatus, a reflected light signal difference of a pair of sub-beams is used in order to control the position adjustment so that the tracking signal becomes zero. On the other hand, in the present invention, it is necessary to measure how many scales and in which direction, so that the reflected light signals of the pair of sub-beams are measured as they are. When the signal magnitude of the first subbeam is S1 and the signal magnitude of the second subbeam is S2, S1 and S2 form a sine wave-like periodic function, respectively, and there is always a constant phase difference between S1 and S2.

When the reference ruler 110 and the light focusing means 120 move relative positions, S1 and S2 each form a sine wave while moving from one scale to the next scale. Accordingly, the number of shifted scales can be obtained by counting the number of cycles generated while measuring the change in the measured S1 and S2 signal magnitudes while moving from one particular position to another. If the scale pitch is p, the number of measurements can be multiplied by p so that the moving distance can be calculated with accuracy within the error range p.

S1 and S2 have a constant phase difference according to the gap d between the first subbeam and the second subbeam, wherein a distance d between the pair of subbeams is disposed in front of the laser light source 131 so that the subbeams are generated. By appropriately rotating the above-described hologram can be adjusted to the desired degree. At this time, the optical measuring means 130, the pitch (p) of the scale formed on the scale portion 110A, and the distance (d) between the pair of sub-beams in the direction parallel to the scale interval direction is expressed by the following equation. It is desirable to form a relationship.

d = k * p ± p / 4 (an integer where k = 0, 1, 2,…)

5 shows S1 and S2 graphs for various d values. FIG. 5 (A) shows a case where the relationship between the interval d between the pair of sub-beams and the graduation pitch p is the above expression d = k * p ± p / 4, whereby the phase difference between S1 and S2 is 90 °. In this case, not only the direction can be detected using the phase difference but also the advantage of being able to double the resolution. FIG. 5 (B) shows a case where the d − p relationship is d = k * p ± p / 2. In this case, since the phase difference becomes 180 °, the direction of movement cannot be detected using the phase difference. It should not have the same value as above. FIG. 5 (C) shows a case in which the d − p relationship is d = k * p ± p / 8. In this case, the phase difference becomes 45 °, so the direction of movement can be detected, but it is advantageous in terms of resolution. There is no number.

(2) push-pull method

The case where the light measuring means 130 uses the push-pull method will be described.

When using the push-pull method, the light measuring means 130, the light measuring means 130, the laser light source 131 emits a single spot of light, the photodiode 132 is 2 The scale passed by the scale unit 110A according to the positional movement size by using the dividing element, and using the magnitude and phase difference of a pair of optical signals measured at both sides of the two-side split light reflected from the reference ruler 110. The number and direction of movement will be measured.

This will be described in more detail with reference to FIG. 6. As described above, in the push-pull method, unlike using three lights in the three-beam method, light of a single spot formed in a relatively large area is emitted. FIG. 6 (A) sequentially shows a process in which light of such a single spot moves through one track or scale.

As described above, in the push-pull method, the reflected light is measured by the photodiode 132 formed of two split elements. At this time, in the position 1 of Fig. 6A, since the right side of the light extends over the track or the scale, the intensity of the reflected light is very low, while the left side of the light extends over the reflector portion, so that the intensity of the reflected light is shown strongly. In the case of the 2 positions in Fig. 6A, that is, when the center position of the track or scale is accurately reached, both left and right while some are over the track and some are over the reflector portion, in which case the light intensity of the reflected light is on the left and right. Will appear the same. In the case of the 3 position of FIG. 6A, the reflected light intensity on the right hand side is high and the reflected light intensity on the left hand side is low, as opposed to the case of the 1 position of FIG. 6A.

FIG. 6B shows a principle of tracking control using a difference value of a pair of optical signals measured at two sides of a data pickup device. In this case as well as in the three-beam method, it is easy to see that only the movement and control near the origin are made in the push-pull method.

6 (C) shows an example of device configuration and an example of a signal obtained at the time of applying the push-pull method in the measurement system of the present invention. Similar to the three-beam method, in this case, two signals can be obtained, the left hand side reflected light and the right hand side reflected light. If each of these is S1 and S2, a graph as shown in Fig. 6C can be obtained similarly to the three-beam method.

In the three-beam method, the phase difference between S1 and S2 can be adjusted as desired by the designer by adjusting the angle between the sub-beams. However, in the push-pull method, such a phase difference is difficult to be introduced. On the other hand, the push-pull method has an advantage that the device configuration can be simplified (because no additional component such as a hologram, etc. is required) than the three-beam method.

(3) DPD method

The case where the optical measuring means 130 uses the DPD method will be described.

When using the DPD method, the optical measuring means 130, the laser light source 131 emits a single spot of light, the photodiode 132 is formed of a four-division element, the reference 110 The number of scales passed by the scale unit 110A according to the positional movement size by using the magnitude and the phase difference of the pair of optical signals formed by the sum of the pair of diagonal optical signals among the four divisions And the direction of movement.

This will be described in more detail with reference to FIG. 7. The DPD method is almost similar to the push-pull method. In the push-pull method, the split-quadrant device is divided as shown in FIGS. 7 (B) and 7 (C). The difference is that you use. At this time, a pair of optical signals are obtained as the sum of the optical signals between the divided elements arranged diagonally to each other. That is, referring to FIGS. 7B and 7C, one optical signal is obtained by adding the optical signals measured in a and c, and another optical signal is obtained by adding the optical signals measured in b and d. You will get

Fig. 7B shows the measurement principle in the case of using the DPD method in the data pickup apparatus, which is also the same as in the three beam method and the push-pull method, and thus description thereof will be omitted.

7 (C) shows an example of device configuration and an example of a signal obtained at the time of applying the DPD method in the measurement system of the present invention. As described above, in the DPD method, by dividing a single spot into four, a pair of optical signals can be obtained as a sum of optical signals between the divided elements arranged diagonally to each other. That is, S1 is obtained by a + c and S2 is obtained by b + d. As in the three-beam method or the push-pull method, S1 and S2 show a graph as shown in FIG. 7 (C). Also, the position measurement is performed by using the number of periods and the phase difference between the two signals as the magnitude of the signal changes. Can be done.

In the DPD method, as in the push-pull method, it is difficult to adjust the phase difference, but as in the push-pull method, the device configuration can be simplified more than in the three-beam method.

As described above, in the present invention, a tracking method generally used in a data pickup device of an optical disc is applied, but a general tracking method is obtained by obtaining a pair of optical signals and performing origin-oriented position control using this difference. Alternatively, the reference ruler 110 and the through measuring the pair of optical signals, by detecting the number of cycles generated according to the change in the signal size of the optical signals and the movement direction detection using the phase difference between the pair of optical signals The magnitude and direction of the positional movement between the light focusing means 120 can be measured with high precision. In particular, in the case of the conventional linear ruler, there is a problem that the cost of the equipment is very high due to the high cost of the manufacture of the reference and the comparator. As a result, the device configuration itself can be easily facilitated, and the device configuration cost can be greatly reduced.

The present invention is not limited to the above-described embodiments, and the scope of application of the present invention is not limited to those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications can be made.

100: measuring system (of the present invention)
110: reference 110A: graduation
111: transparent material 112: reflective material
120: light converging means 130: light measuring means
131: laser light source 132: photodiode
133: calculation unit

Claims (8)

delete delete A reference ruler 110 including a graduated portion 110A having recesses and convex portions alternately arranged at regular intervals;
Light focusing means (120) for irradiating incident light onto the reference (110) and focusing and outputting the reflected light reflected from the reference (110);
Laser light source 131 for injecting light into the light focusing means 120 so that the incident light is irradiated to the reference ruler 110 by the light focusing means 120, the reflected light focused from the light focusing means 120 The optical measuring means 130 includes a plurality of photodiodes 132 for measuring the incident light and a calculation unit 133 for calculating position information using at least one pair of optical signals measured by the photodiodes 132. );
, ≪ / RTI >
When the relative position is moved between the reference member 110 and the light focusing means 120, the light measuring means 130 applies a tracking method, and the photodiode 132 receives the at least one pair of optical signals, respectively. The number of scales and the moving direction of the scales passed by the scale unit 110A according to the position movement size are measured by using the magnitude and phase difference of each of the measured at least one pair of optical signal values, and the movement distance and To calculate the direction,
The light measuring means 130 uses a three-beam method, wherein the light measuring means 130
And a hologram separating the light emitted from the laser light source 131 into ± 1 order light, which is a pair of sub beams formed to the left and right of the 0 th order light and the 0 th order light. ,
By using the magnitude and the phase difference of the optical signal of the pair of sub-beams reflected from the reference 110, the number of scales and the direction of movement passed by the scale unit 110A according to the position movement size is measured. Measuring system.
The method of claim 3, wherein the light measuring means 130
And a pitch (p) of the scale formed in the scale portion (110A) and a space (d) between the pair of sub-beams in a direction parallel to the scale interval direction to form a relationship as shown in the following equation.
d = k * p ± p / 4 (an integer where k = 0, 1, 2,…)
The method of claim 3, wherein the light measuring means 130
And rotate the hologram to adjust the spacing d between the pair of subbeams.
A reference ruler 110 including a graduated portion 110A having recesses and convex portions alternately arranged at regular intervals;
Light focusing means (120) for irradiating incident light onto the reference (110) and focusing and outputting the reflected light reflected from the reference (110);
Laser light source 131 for injecting light into the light focusing means 120 so that the incident light is irradiated to the reference ruler 110 by the light focusing means 120, the reflected light focused from the light focusing means 120 The optical measuring means 130 includes a plurality of photodiodes 132 for measuring the incident light and a calculation unit 133 for calculating position information using at least one pair of optical signals measured by the photodiodes 132. );
, ≪ / RTI >
When the relative position is moved between the reference member 110 and the light focusing means 120, the light measuring means 130 applies a tracking method, and the photodiode 132 receives the at least one pair of optical signals, respectively. The number of scales and the moving direction of the scales passed by the scale unit 110A according to the position movement size are measured by using the magnitude and phase difference of each of the measured at least one pair of optical signal values, and the movement distance and To calculate the direction,
The light measuring means 130 uses a push-pull method, wherein the light measuring means 130
The laser light source 131 emits a single spot of light, and the photodiode 132 is composed of two split elements.
By using the magnitude and phase difference of a pair of optical signals measured at both sides of the divided light is reflected from the reference ruler 110, the number of scales and the moving direction passed by the scale unit 110A according to the position movement size Measurement system characterized by measuring.
A reference ruler 110 including a graduated portion 110A having recesses and convex portions alternately arranged at regular intervals;
Light focusing means (120) for irradiating incident light onto the reference (110) and focusing and outputting the reflected light reflected from the reference (110);
Laser light source 131 for injecting light into the light focusing means 120 so that the incident light is irradiated to the reference ruler 110 by the light focusing means 120, the reflected light focused from the light focusing means 120 The optical measuring means 130 includes a plurality of photodiodes 132 for measuring the incident light and a calculation unit 133 for calculating position information using at least one pair of optical signals measured by the photodiodes 132. );
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When the relative position is moved between the reference member 110 and the light focusing means 120, the light measuring means 130 applies a tracking method, and the photodiode 132 receives the at least one pair of optical signals, respectively. The number of scales and the moving direction of the scales passed by the scale unit 110A according to the position movement size are measured by using the magnitude and phase difference of each of the measured at least one pair of optical signal values, and the movement distance and To calculate the direction,
The optical measuring means 130 uses a DPD method, wherein the optical measuring means 130
The laser light source 131 emits a single spot of light, and the photodiode 132 is formed of a four-division element,
The scale unit 110A according to the positional movement size by using the magnitude and phase difference of a pair of optical signals, in which the light reflected from the reference 110 is a sum of a pair of diagonal optical signals among four divisions. The measuring system, characterized in that for measuring the number of scales and the moving direction in the).
The method of any one of claims 3, 6, 7, wherein the reference ruler 110 is
It is formed of a transparent material that transmits light and is coated on the side of the uneven surface of the transparent material 111 as a material for reflecting light and a transparent material 111 having unevenness formed at the position of the scale portion 110A on one side. A measuring system comprising a reflector (112).

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