JP2013246110A - Rotational angle detection device and surveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational angle detection device capable of detecting an angle with a simple configuration, and a surveying device using the same.SOLUTION: A rotational angle detection device includes a bearing part 3, a rotary shaft 1 rotatably supported on the bearing part 3, an angle detection pattern 8 housed in a shaft space, a reference pattern 16 disposed in the bearing space, an image sensor 13 disposed in the shaft space, light receiving switching means 19 and 20 hung over the shaft space and the bearing space to cause the image sensor 13 to selectively project the projected image of the angle detection pattern 8 and the projected image of the reference pattern 16, and a calculation device 21 for calculating the rotational angle of the rotary shaft 1 on the basis of a signal from the image sensor 13. The calculation device 21 detects the rotational angle of the rotary shaft 1 on the basis of deviation between a signal from the image sensor 13 which has received the reference pattern 16 and a signal from the image sensor 13 which has received the angle detection pattern 8.

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle and a surveying device that uses the rotation angle detection device.

  There is a rotation angle detection device for detecting a rotation angle, and the rotation angle detection device is used as an angle detector for detecting an elevation angle and a horizontal angle in a surveying instrument.

  In recent years, there has been a demand for miniaturization and high accuracy of measuring apparatuses, and further cost reduction.

  For example, there is a total station as a surveying instrument using a rotation angle detection device, and the total station measures the distance to the measurement object, and the elevation angle and horizontal angle of the measurement object.

  Among the measurement errors of the total station, the error of the measurement value caused by the angle error is obtained by multiplying the angle error by the distance to the measurement object, and is proportional to the distance. For this reason, angular accuracy is required to the second. One factor that makes the total station expensive is that angle detection accuracy and rotation accuracy are required to be highly accurate.

  Conventionally, a high-precision encoder is used as a rotation angle detection device used in a surveying instrument. However, the accuracy of parts constituting the encoder and the stability after assembly are problematic, and the high-precision encoder is expensive. . In addition to the manufacturing error and detection error of the encoder itself, the angle error is also caused by the rotation error due to the shake of the rotating shaft. To achieve the required angle detection accuracy, just manage the machining accuracy of a single component. However, it is difficult, and fine adjustment and precision finishing are necessary in the assembled state of the rotating shaft and the bearing portion, which is very expensive.

JP 2009-156773 A

  In view of such circumstances, the present invention provides a rotation angle detection device capable of detecting an angle with a simple configuration, and a surveying device using the rotation angle detection device.

  The present invention includes a bearing portion, a rotation shaft rotatably supported by the bearing portion, a shaft space formed in the rotation shaft, a bearing space formed in the bearing, and the shaft space. The angle detection pattern housed in the bearing space, the reference pattern provided in the bearing space, the image sensor provided in the bearing space, the shaft space and the bearing space, and the angle detection An optical system that forms a projected image of the pattern, a projected image of the reference pattern on the image sensor, and a projected image of the angle detection pattern and a projected image of the reference pattern alternatively to the image sensor. A light receiving switching means for projecting; and a computing device for computing a rotation angle of the rotating shaft based on a signal from the image sensor, the computing device receiving a signal from the image sensor that has received the reference pattern. In which according to the rotation angle detecting device for detecting a rotation angle of the rotary shaft based on a difference between the signal from the image sensor receiving the angle detection pattern.

  Further, the present invention relates to a rotation angle detection device in which the arithmetic device acquires a signal that receives the reference pattern and a signal that receives the angle detection pattern from the image sensor at every measurement time.

  In the invention, it is preferable that the arithmetic unit detects a center blur of the rotating shaft based on a deviation between a signal from the image sensor that has received the reference pattern and a signal from the image sensor that has received the angle detection pattern. The present invention relates to a rotation angle detection device.

  According to the present invention, the angle detection pattern and the reference pattern include a line segment pattern having a ring-shaped track composed of the line segments in which a line segment extending in the radial direction is arranged at a predetermined angular pitch. The present invention relates to a rotation angle detecting device having the same.

  Further, the present invention relates to a rotation angle detecting device in which each of the angle detection pattern and the reference pattern has a centering pattern indicating a center position.

  Further, according to the present invention, the arithmetic device includes a storage unit that stores a signal from the image sensor, and the arithmetic device is provided on the line segment pattern of the stored angle detection pattern image and the reference pattern image, respectively. It is obtained by setting at least one concentric first scanning line, setting a second concentric scanning line on the reference indication pattern of the angle detection pattern image and the reference pattern image, and scanning the scanning line. Based on the obtained signal and based on the signal obtained by scanning the reference designating pattern, a deviation between the angle detection pattern image and the reference pattern image is obtained, and the rotation angle of the rotating shaft is obtained based on both deviations. The present invention relates to a rotation angle detection device that detects

  According to the present invention, the rotation angle between the angle detection pattern image and the reference pattern image is based on the number of line segments existing between the standard indicating patterns of the two images and the phase difference between the line segments of the two images. The present invention relates to a calculated rotation angle detection device.

  The present invention also relates to the rotation angle detection device, wherein the phase difference is an average of phase differences obtained for a required number of line segments.

  Further, according to the present invention, the arithmetic unit sets a division portion at least every 90 ° in the circumferential direction in the angle detection pattern, and a set of two division portions that differ by 180 ° and another set that is orthogonal to the set. The present invention relates to a rotation angle detecting device that is divided into a set of two divided portions and obtains the center of the set of one divided portion from a half value of the phase difference obtained by scanning the other divided portion set.

  According to the present invention, the arithmetic unit rotates the rotation shaft at a predetermined angle pitch in advance, obtains a pattern center from the angle detection pattern every predetermined angle rotation, and further calculates the pattern center and the center of the reference pattern. A rotation angle detecting device that obtains an eccentric circle obtained from a locus of deviation of the center of the pattern, and that a center blur at the time of angle measurement is measured by a deviation between the eccentric circle and the center obtained by the angle detection pattern It is related to.

  Further, according to the present invention, the arithmetic device rotates the rotation shaft at a predetermined angle pitch in advance, obtains the center of both patterns by the angle detection pattern and the reference pattern for each predetermined angle rotation, and further, a deviation between both pattern centers. An eccentric circle obtained from the locus of deviation between the centers of the two patterns is obtained, and the center blur at the time of angle measurement is obtained by the center obtained by the angle detection pattern at each measurement time and the reference pattern The present invention relates to a rotation angle detection device that measures the difference between the difference from the center and the eccentric circle.

  The present invention also provides a base, a base rotatably provided via a first rotating shaft having a vertical axis on the base, and a second rotating shaft having a horizontal axis on the base. A telescope unit provided rotatably, a first rotation angle detection device provided between the first rotation shaft and the base unit and having a configuration equivalent to the rotation angle detection device, and the second The present invention relates to a surveying instrument including a second rotation angle detection device provided between a rotation shaft and the mount and having a configuration equivalent to that of the rotation angle detection device.

  According to the present invention, the bearing portion, the rotating shaft rotatably supported by the bearing portion, the shaft portion space formed in the rotating shaft, the bearing portion space formed in the bearing portion, and the shaft An angle detection pattern housed in the space, a reference pattern provided in the bearing space, an image sensor provided in the bearing space, the shaft space and the bearing space, Alternatively, the projected image of the angle detection pattern, an optical system that forms the projected image of the reference pattern on the image sensor, and the projected image of the angle detection pattern and the projected image of the reference pattern. A light receiving switching means for projecting on the sensor; and a computing device for computing a rotation angle of the rotating shaft based on a signal from the image sensor, the computing device from the image sensor receiving the reference pattern And it detects the rotation angle of the rotary shaft based on the signal and the angle detection pattern on a deviation between the signal from the image sensor that has received can the configuration that does not depend on the accuracy of mounting the image sensor.

  Further, according to the present invention, the arithmetic device obtains a signal that receives the reference pattern and a signal that receives the angle detection pattern from the image sensor at each measurement time. Even if there is a change in the mounting state of the image sensor, measurement can be performed with high accuracy.

  According to the invention, the arithmetic unit is configured to cause the rotation shaft core blur based on a deviation between a signal from the image sensor that has received the reference pattern and a signal from the image sensor that has received the angle detection pattern. Since the rotation angle can be detected while allowing the presence of the core blur, it is not necessary to make the finishing accuracy and assembly accuracy of the parts high, and the cost can be reduced.

  According to the invention, the angle detection pattern and the reference pattern each have a centering pattern indicating a center position, so that the center positions of the angle detection pattern and the reference pattern can be easily detected. .

  According to the invention, the arithmetic unit has a storage unit for storing a signal from the image sensor, and the arithmetic unit is arranged on the line segment pattern of the stored angle detection pattern image and reference pattern image. At least one first concentric scan line is set to each of the above, and a second concentric scan line is set on the reference indication pattern of the angle detection pattern image and the reference pattern image, and the scan line is scanned. Based on the obtained signal and based on the signal obtained by scanning the reference designating pattern, a deviation between the angle detection pattern image and the reference pattern image is obtained, and based on both deviations, the rotation axis Since the rotation angle is detected, the rotation angle exceeding the pattern pitch can be easily detected.

  Further, according to the present invention, the phase difference is an average of the phase differences obtained for a required number of line segments, and therefore, errors in the shape of line segments, uneven brightness, etc. are averaged.

  Further, according to the present invention, the arithmetic unit sets a divided portion at least every 90 ° in the circumferential direction in the angle detection pattern, and has a set of two divided portions that differ by 180 ° and is orthogonal to the set. The angle detection pattern and the reference pattern are obtained by dividing into another set of divided portions and obtaining the center of one divided portion from the half value of the phase difference obtained by scanning the other divided portion set. Even if is eccentric, the center position can be accurately detected.

  According to the invention, the arithmetic unit rotates the rotation shaft at a predetermined angle pitch in advance, obtains a pattern center by the angle detection pattern every predetermined angle rotation, and further calculates the pattern center and the reference pattern. Obtaining the deviation from the center, obtaining an eccentric circle obtained from the locus of deviation of the pattern center, the center blur at the time of angle measurement is measured by the deviation between the eccentric circle and the center obtained by the angle detection pattern, Even if there is a component error or assembly error, the core blur can be accurately measured.

  According to the invention, the arithmetic device rotates the rotation shaft at a predetermined angle pitch in advance, obtains both pattern centers by the angle detection pattern and the reference pattern for each predetermined angle rotation, and further, both pattern centers. And obtaining an eccentric circle obtained by the locus of deviation between the centers of the two patterns, and the center blur at the time of angle measurement is determined by the center obtained by the angle detection pattern at each measurement time and the reference pattern. Since the measurement is performed based on the difference between the obtained center and the eccentric circle, there is a component error and an assembly error, and even when the image sensor is displaced, the core blur can be accurately measured.

  Further, according to the present invention, a base part, a base provided rotatably on the base part via a first rotary shaft having a vertical axis, and a second rotary shaft having a horizontal axis on the base A first rotation angle detection device provided between the first rotation shaft and the base portion and having a configuration equivalent to that of the rotation angle detection device; Since the second rotation angle detection device is provided between the second rotation shaft and the mount and has the same configuration as the rotation angle detection device, the rotation angle can be detected without using an expensive encoder. As a result, the assembly of the rotating shaft and the bearing portion does not cost, and the excellent effect of reducing the manufacturing cost can be achieved.

It is a schematic block diagram of the rotation angle detection apparatus which concerns on the Example of this invention. It is the schematic which shows an example of the illumination means of the said rotation angle detection apparatus. It is a schematic block diagram of the arithmetic unit in a present Example. It is a figure which shows an example of the angle detection pattern used for a present Example, and the pattern for a reference. It is a flowchart of the angle detection of a present Example. It is explanatory drawing in the case of performing angle detection by the said angle detection pattern. It is a wave form diagram of a signal obtained by the angle detection pattern, (A) shows a signal from a line segment pattern, and (B) shows a signal from a reference indication pattern. It is explanatory drawing in the case of calculating | requiring a center position with the said angle detection pattern. It is a front view which shows an example of the surveying apparatus with which the rotation angle detection apparatus which concerns on a present Example was used. It is sectional drawing of this surveying instrument.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, a rotation angle detection apparatus according to an embodiment of the present invention will be described.

  In FIG. 1, reference numeral 1 denotes a rotating shaft whose rotation angle is detected, and the rotating shaft 1 is rotatably supported by a shaft support 3 via a bearing 2.

  A columnar shaft space 4 is formed at the end of the rotating shaft 1 concentrically with the axis of the rotating shaft 1, and the shaft end has a hollow structure. A shaft fitting hole 5 is formed in the shaft support portion 3 concentrically with the shaft center of the rotating shaft 1. The rotary shaft 1 is fitted into the shaft fitting hole 5 via the bearing 2. A storage space 6 is formed in the shaft support portion 3, and the storage space 6 is continuous with the shaft fitting hole 5 and the shaft portion space 4.

  An optical axis 7 is set in the storage space 6, and the optical axis 7 coincides with the axis of the rotary shaft 1. An angle detection pattern 8 is formed on the optical axis 7 from the rotary shaft 1 side. The 1st condensing lens 9, the half mirror 11, the 2nd condensing lens 12, and the image sensor 13 are arrange | positioned. A third condenser lens 15 and a reference pattern 16 are disposed on the branch optical axis 14 branched by the half mirror 11.

  The angle detection pattern 8 and the first condenser lens 9 are housed in the shaft space 4. The optical axis 7a of the first condenser lens 9 coincides with the axis of the rotary shaft 1, and the axis of the rotary shaft 1 coincides with the optical axis 7 (that is, the rotary axis 1 is In a state where there is no core blur or eccentricity with respect to the shaft fitting hole 5, the optical axis 7 a coincides with the optical axis 7.

  The angle detection pattern 8 is at the focal position of the first condenser lens 9, and the optical axis 7 a passes through the center of the angle detection pattern 8 and the angle detection pattern 8 and the first condenser lens 9. And are set.

  The image sensor 13 is held at the focal point of the second condenser lens 12.

  The reference pattern 16 is disposed at the focal point of the third condenser lens 15. The material of the member on which the angle detection pattern 8 and the reference pattern 16 are formed preferably has the same or the same coefficient of thermal expansion as the material of the rotating shaft 1 and the material of the shaft support portion 3.

  The first condenser lens 9 and the third condenser lens 15 have the same magnification, and the second condenser lens 12 has the same or lower magnification as the first condenser lens 9 and the third condenser lens 15. ing. For example, the magnification of the first condenser lens 9 and the third condenser lens 15 is twice, and the magnification of the second condenser lens 12 is one. Therefore, the images of the angle detection pattern 8 and the reference pattern 16 are reduced and projected onto the image sensor 13.

  The standard shape of the angle detection pattern 8 and the reference pattern 16 is circular, and the diameter is about 5 mm to 10 mm. Further, the angle detection pattern 8 and the reference pattern 16 may be the same pattern or different. If they are different, it is only necessary that the angle deviation and the center position deviation be obtained between the patterns.

  The image of the angle detection pattern 8 and the image of the reference pattern 16 are formed on the image sensor 13, respectively, and the image sensor 13 further images the angle detection pattern 8 and the reference pattern. A light receiving switching means 36 (described later) is provided so that 16 images can be selectively received. As the light receiving switching means 36, illumination means 19 and 20 for illuminating the angle detection pattern 8 and the reference pattern 16 are provided separately, and the illumination means 19 and 20 are alternatively turned on. Alternatively, as another light receiving switching means, a shutter is provided across the optical axis 7 and the branched optical axis 14, and the optical axis 7 and the branched optical axis 14 are alternatively selected by the shutter. It is good also as a structure which interrupts | blocks and switches an optical path.

  As the image sensor 13, a CCD, a CMOS sensor or the like, which is an aggregate of pixels, is used. The optical axis 7 is set so as to pass through the origin of the coordinate system (X0-Y0) assumed for the image sensor 13, and each pixel is positioned (coordinate) on the image sensor 13 with the optical axis 7 as the origin. Can be specified.

  The light reception signal from the image sensor 13 is input to the arithmetic device 21. The arithmetic device 21 measures the rotation angle of the rotary shaft 1 and the core blur due to the inclination (inclination angle) of the rotary shaft 1 based on the light reception signal. It is configured like this.

  The angle detection pattern 8 stored in the shaft space 4 and the storage space 6, the first condenser lens 9, the half mirror 11, the image sensor 13, the third condenser lens 15, and the reference The pattern 16 and the like constitute a main part of the rotation angle detection device 18. The first condenser lens 9, the half mirror 11, the second condenser lens 12, and the third condenser lens 15 provide the projection image of the angle detection pattern 8 and the projection image of the reference pattern 16. An optical system for detecting a rotation angle that forms an image on the image sensor 13 is configured.

  FIG. 2 shows an example of the illumination means 19 and 20 of the angle detection pattern 8 and the reference pattern 16, and the illumination means 19 will be described.

  The LEDs 23 are arranged at a predetermined interval on the circumference with the optical axis 7 as the center, and the angle detection pattern 8 is illuminated through the first condenser lens 9. The LED 23 is supported on the shaft support portion 3 side, and power is supplied from the shaft support portion 3 side. Note that one end face of the optical fiber may be arranged at a predetermined interval on the circumference with the optical axis 7 as the center, and illumination light may be incident from the other end face of the optical fiber. Further, illumination is disposed on the opposite side of the angle detection pattern 8 to the first condenser lens 9 and on the opposite side of the reference condenser pattern 16 to the third condenser lens 15, so that the angle detection pattern 8 and the reference pattern 16 are provided. You may make it illuminate from the back side of each.

  Although not shown, the reference pattern 16 is illuminated by the illumination means 20 having the same configuration as the illumination means 19, and as described above, the illumination means for the angle detection pattern 8 is provided. 19. The illumination means 20 of the reference pattern 16 is controlled so as to be alternatively lit.

  As shown in FIG. 3, the arithmetic device 21 mainly includes a signal processing unit 31, an arithmetic control unit 32, an angle detection unit 33, a core blur detection unit 34, a storage unit 35, a light reception switching means 36, and the like. The

  The signal processing unit 31 amplifies the data output from the image sensor 13 or performs signal processing so that it can be stored.

  The storage unit 35 controls the lighting of the illuminating means 19 and 20, controls the signal acquisition timing from the image sensor 13, and the rotation angle calculation for detecting the rotation angle of the rotary shaft 1. A program, a core blur calculation program for detecting the core blur of the rotating shaft 1, a signal processing program for performing signal processing such as extracting a signal necessary for detecting the core blur to detect the rotation angle, etc. Stored. The storage unit 35 stores image data output from the image sensor 13.

  The arithmetic control unit 32 performs arithmetic control based on various programs, controls lighting of the illumination units 19 and 20 by the light reception switching unit 36, and performs synchronous control of signal acquisition from the image sensor 13 and the like.

  The angle detection unit 33 calculates the rotation angle of the rotary shaft 1 based on the signal from the image sensor 13, and is mainly configured by the rotation angle calculation program and the calculation control unit 32. The core blur detection unit 34 calculates a core blur of the rotating shaft 1 based on a signal from the image sensor 13 and is mainly configured by the core blur calculation program and the calculation control unit 32.

  Next, an example of the angle detection pattern 8 and the reference pattern 16 used in this embodiment will be described with reference to FIG. The same pattern is used for the angle detection pattern 8 and the reference pattern 16, and the angle detection pattern 8 will be described below.

  The basic shape of the angle detection pattern 8 is a circle, and the center of the angle detection pattern 8 is configured to substantially match the optical axis of the first condenser lens 9, that is, the optical axis 7a.

  The angle detection pattern 8 includes a circular pattern 25 as a centering pattern at the center, a line segment pattern 26 arranged concentrically with the circular pattern 25 and a reference pattern around the circular pattern 25 as an angle detection pattern. It consists of an instruction pattern 27. The circular pattern 25 is a plurality of true circles (two concentric multiple circles in the figure) drawn with a predetermined line width. The centering pattern may be a pattern that requires the center, and may be a crosshair, for example.

  The line segment pattern 26 has a configuration in which line segments 26a having a predetermined length extending in the radial direction (portions blacked out in the drawing) are arranged at an equal angular pitch n around the entire circumference, and are formed by the line segments 26a. It is a ring-shaped track. In other words, the line segment pattern 26 is obtained by equally dividing a ring having a predetermined track width (predetermined length in the radial direction) into 2n perimeters by 2n radii and forming a line segment 26a for each row. is there. Each line segment 26a is wedge-shaped and has a central angle α of 360 ° / 2n. Further, the center of the line segment pattern 26 is the same as the center of the circular pattern 25.

  The reference designating pattern 27 is formed inside the line segment pattern 26 and has an arc shape concentric with the line segment pattern 26. The reference instruction pattern 27 is divided into a plurality of patterns in the circumferential direction, and is composed of one position instruction pattern 27a and direction instruction patterns 27b arranged on both sides of the position instruction pattern 27a.

  The position indicating pattern 27a has the same central angle as the line segment 26a, and the position indicating pattern 27a is positioned on the same radius line as one of the line segments 26a.

  The direction indicating pattern 27b has a symmetrical position and a symmetrical shape with respect to the position indicating pattern 27a, and has a width (center angle 5α) spanning the three line segments 26a. Note that the width (length in the circumferential direction) of the direction indicating pattern 27b is not limited to the three line segments 26a, but may be different from the width of the line segments 26a.

  The line segment 26a, the position indicating pattern 27a, and the direction indicating pattern 27b may be configured such that light is non-reflective and other portions are reflected, or the line segment 26a, the position indicating pattern 27a, The direction indicating pattern 27b may be reflected and other portions may be non-reflective. In the following description, the line segment 26a, the position instruction pattern 27a, and the direction instruction pattern 27b are described as non-reflective.

  Hereinafter, the operation of the rotation angle detection device 18 will be described.

  The rotation angle detection device 18 can detect the rotation angle and the core blur (rotation of the rotation shaft) accompanying the rotation.

  The angle detection pattern 8 is illuminated by the illumination means 19. The angle detection pattern 8 is projected to the image sensor 13 after being reduced to ½ by the action of the first condenser lens 9 and the second condenser lens 12, and the image sensor 13 detects the received angle detection. A signal corresponding to pattern 8 is generated.

  Similarly, the reference pattern 16 is illuminated by the illuminating means 20, and an image of the reference pattern 16 is projected to the image sensor 13 after being reduced to ½, and the image sensor 13 receives the received reference pattern. A signal corresponding to the pattern 16 is emitted.

  First, the illumination unit 20 is turned on, the image of the reference pattern 16 is acquired by the image sensor 13, and the reference pattern image is stored in the arithmetic unit 21. Next, the illumination unit 20 is turned off, the illumination unit 19 is turned on, and an image of the angle detection pattern 8 is acquired by the image sensor 13.

  Based on the circular pattern 25 of the image of the reference pattern 16, the coarse center position (coordinates in the coordinate system assumed for the image sensor 13) of the reference pattern 16 can be obtained. The reference indication pattern 27 is scanned on the image along the locus (circumferential direction) of the circle centering on the obtained coarse center position, and the rotational position of the reference indication pattern 27 is detected.

  Here, the rotation position of the reference designating pattern 27 indicates coordinates on the image sensor 13. Alternatively, when the coordinate axis assumed for the image sensor 13 is translated to the coarse center position, the reference designating pattern 27 is centered on the coarse center position with respect to the coordinate axis in a predetermined rotation direction (for example, clockwise). Says the rotation angle rotated. This rotation angle indicates a positional shift in the rotation direction of the reference pattern 16 with respect to the coordinate axis assumed for the image sensor 13 (that is, a shift when the reference pattern 16 is installed).

  Further, by scanning the line segment pattern 26 in the circumferential direction around the coarse center position, a frequency component signal having the reference indicating pattern 27 as a reference position is obtained. A rotation angle is obtained based on the signal of the frequency component, and further, a divided portion is set at least every 90 °, and a set of two divided portions different by 180 ° and the other divided portion that is orthogonal to the set The precise center position of the reference pattern 16 is obtained from half of the phase difference obtained by scanning the center of the one set of divided portions and the other set of divided portions.

  Next, an image of the angle detection pattern 8 is acquired by the image sensor 13. Similarly to the case of the reference pattern 16, the coarse center position is obtained, the reference designating pattern 27 and the line segment pattern 26 are scanned in the circumferential direction around the coarse center position, and the angle detection pattern 8. Rotation position and precise center position are required.

  The precise center position obtained by the angle detection pattern 8 and the precise center position obtained by the reference pattern 16 are compared, and the positional deviation (deviation) on the image sensor 13 of both precise center positions is obtained. The rotation position of the reference indication pattern 27 of the angle detection pattern 8 or the rotation position of the reference indication pattern 27 of the reference pattern 16, and the frequency component of the line segment pattern 26 of the angle detection pattern 8 or the reference pattern The frequency components of the 16 line segment patterns 26 are corrected by the deviation. A coarse rotation angle is obtained by comparing the rotation position of the reference indication pattern 27 of the angle detection pattern 8 after correction with the rotation position of the reference indication pattern 27 of the reference pattern 16, and the angle detection pattern 8 of the angle detection pattern 8 is further corrected. The phase difference between the frequency component of the line segment pattern 26 and the frequency component of the line segment pattern 26 of the reference pattern 16 is obtained, and an angle (precise rotation angle) less than one line segment pattern is obtained based on the phase difference, A highly accurate rotation angle is measured by a combination of a coarse rotation angle and a precision rotation angle.

  Further, when obtaining the rotation angle after a predetermined time has elapsed, if the elapsed time is not long, the rotation position of the reference indicating pattern 27 and the frequency component of the line segment pattern 26 are acquired only for the angle detection pattern 8. In the case where the elapsed time is long, similarly, the rotation position of the reference indication pattern 27 obtained by the reference pattern 16 is compared with the frequency component of the line segment pattern 26, and the high-precision rotation after a predetermined time has elapsed. The angle can be measured.

  Further, the amount of rotation at the elapsed time is obtained by comparing the rotation angle obtained for the angle detection pattern 8 before the lapse of a predetermined time with the rotation angle of the angle detection pattern 8 obtained after the lapse of the predetermined time. The rotational speed can be obtained by differentiating the rotation amount with the elapsed time.

  The detection of the rotation angle and the detection of the core blur will be specifically described with reference to FIGS.

  In STEP: 01 and STEP: 02, the reference pattern image and the angle detection pattern image of the rotating shaft 1 are acquired and stored in the storage unit 35, respectively. For each of the stored reference pattern image and the angle detection pattern image, a scan line (scan line) is set on the image signal (on the data stored in the storage unit 35), and along the scan line. Scanned. Here, since the scanning line is a virtual line set on the data, an arbitrary number can be set at an arbitrary position, and the measurement accuracy can be improved by increasing the number of the scanning lines. .

  6 shows the relationship between the reference pattern image, the circular pattern 25, the line segment pattern 26, the reference designating pattern 27 and the scanning line in the angle detection pattern image. In FIG. The Y axis represents a coordinate system (XY) having the origin of the center of the reference pattern image or the angle detection pattern image. The coordinate axes shown here are obtained by translating the X0 axis and Y0 axis set on the image sensor 13, and the center of the angle detection pattern 8, the reference pattern 16 and the optical axis 7 are aligned. In this state, the X and Y axes shown in FIG. 6 coincide with the X0 and Y0 axes assumed for the image sensor 13.

  In FIG. 6, the line segment 26a, the position indicating pattern 27a, and the direction indicating pattern 27b are not painted black.

  Hereinafter, the positions (center position and rotational position) of the reference pattern image and the angle detection pattern image in the image sensor 13 are obtained. Either may be obtained first, but in the following procedure, a case will be described in which a position is first obtained for the reference pattern image and then a position is obtained for the angle detection pattern image.

  (Step 03) First, with respect to the circular pattern 25, scanning lines 37a and 37b are set parallel to the X0 axis and the Y0 axis, scanned along the scanning lines 37a and 37b, and positioned on the scanning lines 37a and 37b. A pixel signal is acquired. The circular pattern 25 is detected based on the acquired pixel signal.

  (Step 04) By detecting the circular pattern 25, the center of the circle, that is, the center position on the X0-Y0 coordinates of the reference pattern 16 (hereinafter, coarse center position) is obtained, and the coordinates of the coarse center position are obtained. By obtaining the deviation with respect to the origin, the positional deviation of the reference pattern 16 of the rotation angle detecting device 18 is obtained. This positional deviation is measured as an installation error of the reference pattern 16.

  Here, since the circle pattern 25 is a multiple circle and a plurality of the scanning lines 37 are set, a plurality of data can be acquired, and a plurality of coarse center positions are obtained. The accuracy is improved by averaging a plurality of obtained coarse center positions.

  The scanning lines 38a, 38b, 38c and the scanning line 39 of the line segment pattern 26 centered on the obtained coarse center position are set to concentric multiple circles (four multiple circles in the figure). The starting point (starting point) (0 ° position) for scanning may be set at any position on the scanning lines 38a, 38b, 38c, but at the reference position in the coordinate system (XY). For example, it is set at a point intersecting the Y axis.

  (Step 05) With respect to the reference instruction pattern 27, the scanning line 39 is scanned, and a signal on the scanning line 39 is acquired (see FIG. 7B). FIG. 7B shows a state in which the reference instruction pattern 27 has been scanned all around a plurality of times, and the signal of the reference instruction pattern 27 is acquired every 360 °.

  (Step 06) The scanning lines 38a, 38b, and 38c are scanned with respect to the line segment pattern 26.

  FIG. 7A shows a signal output obtained when the line segment pattern 26 is scanned. FIG. 7A scans the line segment pattern 26 three times, and scan lines are scanned every rotation. The signal obtained when the scanning line 38a is changed to the scanning line 38b and the scanning line 38b is changed to the scanning line 38c (when each scanning line is scanned all around) is shown, and the signals are shown continuously. Yes.

  As shown in FIG. 4, in the line segment pattern 26, blank portions and line segment patterns 26 are alternately formed, and one period is formed by the blank portions and the line segment pattern 26. Therefore, by scanning the line segment pattern 26, a signal including a frequency component (hereinafter, frequency signal) is obtained. Further, the scanning lines 38a, 38b, and 38c are scanned all around, and the obtained frequency signals are averaged to obtain a coarse frequency signal having a highly accurate period (phase).

  FIG. 7A shows a state in which the position of the scanning start point (0 °) and the phase of the frequency component 0 ° do not match and the phase is shifted.

  (Step 07) Based on the signal obtained by the reference designating pattern 27 and the signal obtained by the line segment pattern 26, the rotational position of the reference pattern image (rotation angle with reference to the coordinate system (XY)) is obtained. .

Referring to FIG. 7B, the signal of the reference designating pattern 27 is on the minus side from the scanning start point (0 °), and the number of the line segments 26a, that is, the number of frequencies (N) is counted from the scanning start point. A rough rotation angle is required. Further, since the phase of the frequency signal is shifted with respect to the scanning start point, the fractional angle can be obtained by obtaining the phase difference σ.
Therefore, the rotation angle of the reference pattern image is
N × 360 ° / n + σ × 360 ° / n.

  STEP: 08 The line segment pattern 26 is equally divided (at least divided into four) in the circumferential direction with reference to either the position indicating pattern 27a or the direction indicating pattern 27b of the reference indicating pattern 27. FIG. 8 shows a case of four divisions. The divided parts belonging to one of the 180 ° ranges are designated as A1 and A2, the other divided parts belonging to the 180 ° range as B1 and B2, and the divided parts A1, the divided parts B1, and the divided parts A2 and The division parts B2 are opposed to each other. Accordingly, the corresponding divided portions are each 180 degrees out of phase.

  (Step 09) The line segment pattern 26 is scanned all around along the scanning line 38a, and the signal of the line segment 26a belonging to each divided portion is obtained. Similarly, the entire circumference is scanned along the scanning lines 38b and 38c, and the signal of the line segment 26a belonging to each divided portion is acquired. By averaging the acquired signals for each divided portion, a high-accuracy frequency signal (hereinafter referred to as (divided portion frequency signal)) that cancels the pattern forming error of the line segment 26a is obtained.

  (Step 10) When the phase is detected for all the divided parts, the deviation (displacement amount) on the X0-Y0 coordinate of each divided part based on the detected phase (or the coordinates of the center of the divided part on the X0-Y0 coordinate) ) The center position of the line segment pattern image is obtained based on the amount of displacement obtained from the divided portion. The center position obtained here is more accurate than the coarse center position obtained based on the circular pattern 25 (hereinafter referred to as a precision center position).

  (Step 11) The precise rotation position of the reference indicating pattern 27 is obtained using the obtained precise center position as a reference. That is, a highly accurate XY coordinate system having a precise center position as an origin is obtained, and the phase difference of the frequency signal is obtained in the XY coordinate system, and high-precision rotation is performed based on the phase difference. A corner is required.

  (Step 12) With respect to the reference pattern 16, when the precise center position of the reference pattern image, the precise rotational position of the reference indicating pattern 27, the precise frequency signal, and the phase difference of the precise frequency signal can be acquired, the angle detection pattern Similarly, for the image, the precise center position, the precise rotational position of the reference designating pattern 27, the precise frequency signal for the line segment pattern 26, and the phase difference between the precise frequency signals are acquired.

  The steps from STEP: 03 to STEP: 11 are also performed on the angle detection pattern image, and (precise center position) ′, (rotation angle) ′ (hereinafter, “about the angle detection pattern 8” is attached). Desired.

  (Step 13) The deviation between the center position of the reference pattern 16 and the angle detection pattern 8, that is, the center blur, is detected by obtaining the deviation between the precise center position and the (precise center position) '. ) ′ To obtain the difference in rotation angle between the reference pattern 16 and the angle detection pattern 8, that is, the rotation angle (rotation amount) of the rotary shaft 1.

  Note that the line segment pattern 26 formed in the angle detection pattern 8 and the reference pattern 16 only needs to be able to detect a phase difference, and therefore the line segment pattern formed in the angle detection pattern 8 and the reference pattern 16. 26 may not be formed on the entire circumference, but may be formed within a range of a predetermined angle. Further, even when formed on the entire circumference, the phase difference may be obtained for the required number of line segments 26a, and the angle may be detected by the averaged phase difference.

  The angle detection pattern 8 and the reference pattern 16 may contain errors, but the entire circumference of the scanning line 38 is 360 °, and this value does not change. Therefore, by acquiring a signal over the entire circumference and detecting the angle over the entire circumference, the error factors included in the angle detection pattern 8 and the reference pattern 16 are canceled out, and a highly accurate angle detection can be performed. .

  In the above measurement, since the angle detection and the core blur measurement are always performed by comparing the reference pattern 16 and the angle detection pattern 8, even if the image sensor 13 rises in temperature and changes during measurement, The error is offset. Therefore, even in a measurement environment with a large temperature difference, highly stable measurement with high stability and reliability is possible.

  The temperature rise of the image sensor 13 is a phenomenon at the beginning of measurement, and becomes stable after a predetermined time has elapsed after the start of measurement. In addition, a drift phenomenon of the electric circuit appears frequently at the beginning of the measurement and decreases after a predetermined time. Therefore, the acquisition of the image of the reference pattern 16 by the image sensor 13 is performed at the initial stage of the measurement by comparing the reference pattern 16 and the angle detection pattern 8 with the image acquired at substantially the same time, and a predetermined time has elapsed. After that, the reference pattern image acquired at a predetermined time interval may be compared with the angle detection pattern image at the time of measurement.

  In this embodiment, the core blur can be measured with higher accuracy using the angle detection pattern 8 and the reference pattern 16.

  This will be described with reference to FIG. The angle detection pattern 8 will be described below, but the reference pattern 16 is the same. In the figure, the line segment 26a, the position indicating pattern 27a, and the direction indicating pattern 27b are not painted black.

  First, regarding the angle detection pattern 8, the scanning line 38a will be described.

  As described above, the line segment pattern 26 is circumferentially divided into the divided portion A1, the divided portion A2, and the divided portion by using either the position indicating pattern 27a or the direction indicating pattern 27b of the reference indicating pattern 27 as a reference. Divided into four parts, part B1 and part B2.

  Similarly to the case of detecting the angle with high accuracy, the (divided portion frequency signal) is obtained for each divided portion. For example, (division part frequency signal) is obtained for the division part A1. Further, the (division part frequency signal) of the division part B1 having a phase difference of 180 ° is obtained.

  Further, the division unit A2 and the division unit A2 and the division unit B2 (division unit frequency signals) that are 90 degrees out of phase with each other are obtained.

  Next, a phase difference is obtained for each (divider frequency signal) of the divider A1, the divider B1, the divider A2, and the divider B2.

  The phase difference obtained between the divided portions is set as a shift amount on the orthogonal coordinates set on the image sensor 13.

  Based on the calculated deviation amount, the center position on the orthogonal coordinates of each of the divided portions of the dividing portion A1, the dividing portion B1, the dividing portion A2, and the dividing portion B2 can be calculated.

  A straight line (Y center line) connecting the center of the divided part A1 and the center of the divided part B1 and a straight line (X center line) connecting the center of the divided part A2 and the center of the divided part B2 are obtained. The center position of the X center line (the center point of the X center line) and the center position of the Y center line (the center point of the Y center line) are the center positions of the angle detection pattern 8, respectively, and are orthogonal coordinates (XY coordinate system). Coordinate position) is calculated.

The X center line and the Y center line are expressed by the following formulas.
X center line = [Φ (A1) −Φ (B1)] / 2
Y center line = [Φ (A2) −Φ (B2)] / 2
Here, [Phi] (A1), [Phi] (A2), [Phi] (B1), [Phi] (B2) indicate phases in the respective divided portions.

  Similarly, the center coordinates of the scanning lines 38b and 38c are obtained, and the center coordinates of the angle detection pattern 8 are obtained with higher accuracy by averaging all the center coordinates.

  Similarly to the obtained coordinates of the center position, the size of the center blur of the angle detection pattern 8 with respect to the coordinates of the center position obtained from the reference pattern 16 and the direction of the center blur can be calculated.

  It is preferable that the rotating shaft 1 has no core blur at the time of rotation. However, it is extremely difficult to make the core blur close to 0 by increasing the component accuracy and the assembly accuracy, and the manufacturing cost increases. . The core blur described here means rattling of the rotating shaft.

  In the present embodiment, the center axis of the rotating shaft 1 is allowed to be detected, and the angle can be detected with higher accuracy.

  First, with the initial data obtained and the center coordinates of the reference pattern 16 obtained, the rotating shaft 1 is rotated at a predetermined angular pitch (for example, 5 ° pitch), and the angle detection pattern is rotated at each pitch rotation. 8 is obtained, the center coordinate is compared with the center coordinate of the reference pattern 16, and a deviation is obtained. The obtained deviation is stored in the storage unit 35 in association with the rotation angle.

  The rotation shaft 1 is rotated 360 ° to obtain a deviation from the center of the reference pattern 16 for one rotation. The locus of this deviation coincides with the center coordinates of the reference pattern 16 as a point if the rotation center of the rotary shaft 1 completely matches the optical axis 7 and there is no center blur.

  Actually, since the center blur occurs with the rotation of the rotary shaft 1, the locus drawn by the central axis according to the rotation is a circle or an ellipse (hereinafter referred to as an eccentric circle due to the core blur). However, the eccentric circle due to the core blur is highly reproducible in terms of mechanism, and the direction and amount of the core blur can be accurately grasped by the locus of the deviation. Therefore, by detecting the eccentric circle due to the core blur and correcting the measurement angle, it is possible to measure the angle with high accuracy even for the rotating shaft having the core blur.

  Further, since the reference pattern 16 is fixed and is not displaced by the rotation of the rotary shaft 1, the center position obtained by the reference pattern 16 is set as a default value, and the default value and the pitch obtained for each pitch rotation are set. The center blur amount may be obtained from the deviation from the center of the angle detection pattern 8.

  Similarly, when there is an error in the pattern attachment, the locus drawn by the central axis in accordance with the rotation draws an eccentric circle due to the error, and this can also be corrected in the same manner as described above.

  Furthermore, once the locus of the deviation is acquired and stored as correction information, the rotational angle of the rotary shaft 1 can be measured accurately, and the core blur of the rotary shaft 1 is further enlarged for some reason. In such a case, by obtaining a difference from the obtained deviation, it is possible to easily correct even when enlarged. In this case, for example, even when the image sensor 13 is deformed due to temperature, by using the correction information as a reference, highly reliable and stable measurement can be performed.

  Furthermore, the case where the core blur is measured with high accuracy will be described. In the case of measuring the core blur with high accuracy, for each measurement, the angle detection pattern 8 is evenly divided in the circumferential direction to set divided portions, for example, every 90 °. It is divided into a combination of two divided parts different from each other by 180 °, and a combination having a part arranged in a relationship orthogonal to the combined divided parts. Each combination portion is scanned, and the center of the portion forming the combination is obtained from each average value. Furthermore, by obtaining from the half value of the phase difference obtained at each center, the obtained center coordinate is obtained, and at the same time, the center coordinate of the reference pattern 16 is obtained, and the center coordinate of the angle detection pattern 8 is obtained. A deviation from the center coordinate of the reference pattern 16 is obtained.

  Since the average center coordinates are used, illumination unevenness and quantization error due to the pixels of the image sensor 13 are reduced, and highly accurate angle measurement based on highly accurate detection of the core blur becomes possible.

  In the embodiment, the image of the angle detection pattern 8 and the reference pattern 16 is acquired by the image sensor 13, and the rotation angle of the angle detection pattern 8 and the reference pattern 16 is acquired from each acquired image. The rotation amount of the rotary shaft 1 (rotation angle of the shaft) and the core blur were obtained by comparing the detected rotation angles. The reference pattern image obtained by the image sensor 13 and the angle detection pattern image were obtained. And the rotation angle of the rotary shaft 1 and the core blur may be measured from the deviation between the two pattern images.

  9 and 10 show a case where the rotation angle detection device 18 according to the present embodiment is used in a surveying device, and a total station 40 is shown as an example of the surveying device.

  A base part 43 is provided in the leveling part 41 via a leveling screw 42. A base 44 is provided on the base 43, and a telescope 45 including an optical system is supported on the base 44. A distance measuring unit (not shown) is provided inside the telescope unit 45. The distance measuring unit is configured to irradiate distance measuring light from the telescope unit 45 to the measuring object, receive distance measuring light reflected by the measuring object, and perform distance measurement based on the received reflected light.

  The base portion 43 can be leveled by the leveling screw 42 so as to be horizontal. The gantry 44 can rotate around a vertical axis, and the telescope unit 45 can rotate around a horizontal axis. The gantry 44 is provided with an operation input unit 47 having a display unit 46. The display unit 46 displays the operating state of the total station 40 or a measured value of the distance to the measuring object.

  A base base 48 is provided on the upper surface of the base portion 43, and a bearing 52 that protrudes upward is provided at the center of the base base 48. A horizontal rotating shaft 51 is rotatably fitted to the bearing 52 via a bearing portion 49, and a housing 53 of the gantry 44 is fixed to the horizontal rotating shaft 51. The gantry base 48 functions as a lower cover that constitutes a part of the base portion 43 that supports the housing 53 and closes the lower opening of the housing 53.

  A horizontal rotation gear 54 is fixed to the bearing 52, and a horizontal rotation drive gear 55 is engaged with the horizontal rotation gear 54. The horizontal rotation drive gear 55 is fixed to an output shaft of a horizontal rotation motor 56, and the horizontal rotation drive gear 55 is rotated by the horizontal rotation motor 56, whereby the housing is connected via the horizontal rotation gear 54. 53 rotates in the horizontal direction around the horizontal rotation shaft 51. The horizontal rotation motor 56 is fixed to the casing 53, and the horizontal rotation motor 56 and the casing 53 rotate integrally.

  A lower end portion of the horizontal rotating shaft 51 is hollow, and a first shaft portion space 57 is formed by the hollow portion. A horizontal angle detection pattern 58 and a horizontal first condenser lens 59 are accommodated in the first shaft space 57, and the horizontal angle detection pattern 58 and the horizontal first condenser lens 59 are axes of the horizontal rotation shaft 51. It is provided above.

  A shaft holder 61 is provided on the lower surface of the center portion of the gantry base 48, and the shaft center of the shaft holder 61 matches the shaft center of the horizontal rotation shaft 51. A bearing space 62 is formed inside the shaft holder 61, and a horizontal second condenser lens 63 and a horizontal image sensor 64 are housed in the bearing space 62, and the horizontal second condenser lens 63 and the horizontal The image sensor 64 is provided on the shaft center of the shaft holder 61.

  Further, a horizontal half mirror 65 is provided between the horizontal second condenser lens 63 and the horizontal image sensor 64 on the axis of the shaft holder 61, and on the reflected optical axis of the horizontal half mirror 65. A horizontal third condenser lens 66 and a horizontal reference pattern 67 are provided.

  The horizontal angle detection pattern 58, the horizontal first condenser lens 59 and the horizontal second condenser lens 63, the horizontal image sensor 64, the horizontal half mirror 65, the horizontal third condenser lens 66, and the horizontal reference The pattern 67 constitutes a main part of a horizontal rotation angle detection device 68 that detects a horizontal angle.

  The horizontal first condenser lens 59, the horizontal second condenser lens 63, the horizontal half mirror 65, and the horizontal third condenser lens 66 correspond to the horizontal angle detection pattern 58 and the horizontal reference pattern 67. A horizontal rotation angle detecting optical system for forming a projected image on the horizontal image sensor 64 is configured.

  The telescope unit 45 is provided with a vertical rotation shaft 71 extending horizontally from the left and right ends. The vertical rotation shaft 71 is supported by the casing 53 via a bearing 72, and the telescope unit 45 is rotated vertically. The shaft 71 can rotate in the vertical direction.

  A vertical rotation gear 73 is fixed to one end of the vertical rotation shaft 71, and a vertical rotation drive gear 74 is engaged with the vertical rotation gear 73. The vertical rotation drive gear 74 is fixed to the output shaft of the vertical rotation motor 75, and the telescope unit 45 is moved via the vertical rotation drive gear 74 and the vertical rotation gear 73 by driving the vertical rotation motor 75. It is rotated around the vertical rotation shaft 71.

  A second shaft portion space 76 concentric with the vertical rotation shaft 71 is formed at the other end portion of the vertical rotation shaft 71, and a vertical angle detection pattern 77 and a vertical first condensing portion are formed in the second shaft portion space 76. A lens 78 is housed, and the vertical angle detection pattern 77 and the vertical first condenser lens 78 are provided on the axis of the vertical rotation shaft 71.

  A cylindrical holder support 79 is provided concentrically with the other end of the vertical rotating shaft 71 so as to project toward the inside of the casing 53, and a shaft holder 81 is fitted at the tip of the holder support 79. . The shaft holder 81 is formed with a bearing space 82 concentric with the axis of the vertical rotation shaft 71, and the vertical second condenser lens 83 and the vertical image sensor 84 are accommodated in the bearing space 82. The vertical second condenser lens 83 and the vertical image sensor 84 are provided on the axis of the vertical rotation shaft 71.

  A vertical half mirror 85 is provided between the vertical second condensing lens 83 and the vertical image sensor 84 on the axis of the vertical rotation shaft 71, and the vertical second mirror 85 is arranged on the reflected optical axis of the vertical half mirror 85. Three condensing lenses 86 and a vertical reference pattern 87 are provided.

  The vertical angle detection pattern 77, the vertical first condenser lens 78, the vertical second condenser lens 83, the vertical image sensor 84, the vertical half mirror 85, the vertical third condenser lens 86, and the vertical reference. The pattern 87 constitutes a main part of the vertical rotation angle detection device 88 that detects the vertical angle (the elevation angle).

  The vertical first condenser lens 78, the vertical second condenser lens 83, the vertical half mirror 85, and the vertical third condenser lens 86 correspond to the vertical angle detection pattern 77 and the vertical reference pattern 87. An optical system for detecting a vertical rotation angle for forming a projected image on the vertical image sensor 84 is configured.

  The operation of the total station 40 will be described. The operation of the horizontal rotation angle detection device 68 and the vertical rotation angle detection device 88 is the same as the operation of the rotation angle detection device 18, and thus the description thereof is omitted.

  First, the total station 40 is leveled by the leveling screw 42. After leveling, the total station 40 is set as a reference position.

  Next, in order to collimate the telescope unit 45 to the measurement object, the horizontal rotation motor 56 is driven to rotate the casing 53 in the horizontal direction. The horizontal rotation angle of the casing 53 is detected by the horizontal rotation angle detection device 68. Further, the shaft rotation (shaft inclination) of the rotating shaft is also detected simultaneously by the horizontal rotation angle detecting device 68, and the detected horizontal angle is corrected based on the detected shaft shaking.

  Further, the vertical rotation motor 75 is driven, and the telescope unit 45 is rotated in the vertical direction. The vertical rotation angle of the telescope unit 45 is detected by the vertical rotation angle detection device 88, and the axial rotation of the vertical rotation shaft 71 is also detected simultaneously by the vertical rotation angle detection device 88. Similarly, the detected vertical angle is corrected based on the detected shaft shake.

  When the collimation of the telescope unit 45 is completed, distance measuring light is emitted from the telescope unit 45 and the distance to the measurement object is measured. At the same time, the horizontal rotation angle detection device 68 and the vertical rotation angle detection device 88 Angles and elevation angles are measured.

  In the surveying instrument according to the present embodiment, the horizontal angle and the elevation angle can be measured with high accuracy without using an expensive encoder, and the horizontal rotation angle detection device 68 and the vertical rotation angle detection device 88 do not require manufacturing accuracy. Therefore, it can be manufactured at low cost and the production cost of the surveying instrument can be reduced.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Bearing 3 Shaft support part 7 Optical axis 8 Angle detection pattern 9 1st condensing lens 12 2nd condensing lens 13 Image sensor 15 3rd condensing lens 16 Reference pattern 18 Rotation angle detection apparatus 19 Illumination means 20 Illuminating means 21 Calculation device 25 Circular pattern 26 Line segment pattern 27 Reference indication pattern 31 Signal processing unit 32 Calculation control unit 33 Angle detection unit 34 Core blur detection unit 35 Storage unit 37 Scan line 38 Scan line 39 Scan line 40 Total station 43 Base Unit 44 gantry 45 telescope unit 51 horizontal rotation shaft 53 housing 62 bearing space 63 horizontal second condenser lens 64 horizontal image sensor 68 horizontal rotation angle detector 71 vertical rotation shaft 76 second shaft space 77 vertical angle detection pattern 78 Vertical first condenser lens 82 Bearing space 83 Vertical second condenser Lens 87 vertical reference pattern 88 vertical rotation angle detecting device

Claims (12)

  A bearing portion, a rotating shaft rotatably supported by the bearing portion, a shaft portion space formed in the rotating shaft, a bearing portion space formed in the bearing portion, and the shaft portion space. An angle detection pattern, a reference pattern provided in the bearing space, an image sensor provided in the bearing space, a projection image of the angle detection pattern across the shaft space and the bearing space And an optical system for forming a projected image of the reference pattern on the image sensor, and a light receiving switching for alternatively projecting the projected image of the angle detection pattern and the projected image of the reference pattern onto the image sensor. And a computing device that computes the rotation angle of the rotating shaft based on a signal from the image sensor, the computing device receiving the reference pattern and the signal from the image sensor and the angle Rotation angle detecting device and detects the rotation angle of the rotary shaft based on a difference between the signal from the image sensor that has received the pattern out.   The rotation angle detection device according to claim 1, wherein the arithmetic device acquires a signal received from the image sensor for the reference pattern and a signal received from the angle detection pattern for each measurement.   The arithmetic unit detects a center blur of the rotating shaft based on a deviation between a signal from the image sensor that has received the reference pattern and a signal from the image sensor that has received the angle detection pattern. The rotation angle detection device according to claim 2.   The angle detection pattern and the reference pattern have a line segment pattern in which a line segment extending in the radial direction is arranged on the entire circumference at a predetermined angle pitch, and has a ring-shaped track constituted by the line segment. The rotation angle detection device according to claim 3.   The rotation angle detection device according to claim 1, wherein each of the angle detection pattern and the reference pattern has a centering pattern indicating a center position.   The arithmetic device includes a storage unit that stores a signal from the image sensor, and the arithmetic device performs first concentric scans on the line segment patterns of the stored angle detection pattern image and reference pattern image, respectively. Based on a signal obtained by setting at least one line, setting a concentric second scanning line on the reference indication pattern of the angle detection pattern image and the reference pattern image, and scanning the scanning line And calculating a deviation between the angle detection pattern image and the reference pattern image based on a signal obtained by scanning the reference designating pattern, and detecting a rotation angle of the rotating shaft based on both deviations. The rotation angle detection device according to any one of claims 1 to 5.   The rotation angle between the angle detection pattern image and the reference pattern image is calculated on the basis of the number of line segments existing between the reference indicating patterns of the two images and the phase difference between the line segments of the two images. 6 shows a rotation angle detection device.   The rotation angle detection device according to claim 7, wherein the phase difference is an average of phase differences obtained for a required number of line segments.   The arithmetic unit sets a divided portion at least every 90 ° in the circumferential direction in the angle detection pattern, sets two divided portions that are 180 ° different from each other, and another divided portion set orthogonal to the set. 7. The rotation angle detection device according to claim 2, wherein the center of one division portion is determined from a half value of a phase difference obtained by scanning the other division portion set. The arithmetic device rotates the rotation axis at a predetermined angle pitch in advance, obtains a pattern center by the angle detection pattern every predetermined angle rotation, and further obtains a deviation between the pattern center and the center of the reference pattern, The rotation angle detection device according to claim 9, wherein an eccentric circle obtained from a locus of deviation of the pattern center is obtained, and a core blur at the time of angle measurement is measured by a deviation between the eccentric circle and a center obtained from the angle detection pattern.
(The center obtained from the reference pattern in advance is fixed as the default value. When the image sensor is not deformed) The arithmetic unit rotates the rotation axis at a predetermined angle pitch in advance, obtains both pattern centers by the angle detection pattern and the reference pattern for each predetermined angle rotation, further obtains a deviation between the two pattern centers, An eccentric circle obtained by the locus of deviation of the pattern center is obtained, and the center blur at the time of angle measurement is the difference between the center obtained by the angle detection pattern and the center obtained by the reference pattern at each measurement time. The rotation angle detection device according to claim 9, wherein the rotation angle detection device is measured by a deviation from the eccentric circle.
(When there is deformation in the image sensor) A base part, a base provided rotatably on the base part via a first rotating shaft having a vertical axis, and a base provided rotatably on a second rotating shaft having a horizontal axis A telescope unit, the first rotation shaft and the base unit, the first rotation angle detection device having the configuration of claim 1, and the second rotation shaft and the gantry A surveying apparatus, comprising: a second rotation angle detection device provided and having the configuration of claim 1.