JP6962194B2 - Encoder device, drive device, stage device, robot device and information acquisition method - Google Patents

Description

The present invention relates to an encoder device, a drive device, a stage device, a robot device, and an information acquisition method.

Encoder devices that detect rotation information are mounted on various devices such as drive devices (eg, motor devices). The encoder device detects, for example, light from a scale provided on a rotation shaft and acquires rotation information. Further, as an encoder device, there is an encoder device that uses a polarizing plate instead of a scale (see, for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 2001-221660

When it is desired to obtain the rotation information of the rotation axis with high accuracy, a scale in which a precise optical pattern is accurately formed is used. However, since it is not easy to form a precise optical pattern and the manufacturing cost is high, an encoder that requires a simple configuration and rotation information with a certain degree of accuracy is also required.

According to the aspect of the present invention, an image pickup unit that images a mark including a line whose direction changes due to rotation of the rotation axis, an image of the line obtained by the image pickup unit, and a predetermined line set in the image by the image pickup unit. An encoder device including a processing unit for obtaining rotation information of a rotation axis according to the number of intersections of the above is provided. Further, according to the aspect of the present invention, an imaging unit that captures a mark including an injured line whose direction changes due to the rotation of the rotating shaft, a processing unit that obtains rotation information of the rotating shaft from the image obtained by the imaging unit, and a processing unit. An encoder device comprising the above is provided. Further, according to the aspect of the present invention, the mark is formed by a plurality of imaging units that image a mark including a line whose direction changes due to rotation of the rotation axis, and an image obtained by at least one imaging unit of the plurality of imaging units. An encoder device including a processing unit for determining a rotation position is provided. Further, according to the aspect of the present invention, the mark including the line whose direction changes due to the rotation of the rotation axis is imaged, the image of the line obtained by the image, and the predetermined line set in the captured image. An information acquisition method including obtaining rotation information of a rotation axis by the number of intersections with and is provided. According to the first aspect of the present invention, the rotation information of the rotation axis is obtained by using the image pickup unit that images a mark including at least one line whose direction changes due to the rotation of the rotation axis and the image obtained by the image pickup unit. An encoder device including a processing unit for calculating is provided.

According to the second aspect of the present invention, there is provided a drive device including the encoder device of the first aspect and a drive unit that supplies a drive force to the rotating shaft.

According to the third aspect of the present invention, there is provided a stage device including a moving body and a driving device of the second aspect for moving the moving body.

According to the fourth aspect of the present invention, there is provided a robot device including the drive device of the second aspect and an arm that is relatively moved by the drive device.

According to the fifth aspect of the present invention, a mark including at least one line provided on the rotating shaft of the driving device and whose direction changes depending on the rotation of the rotating shaft is imaged, and the mark is used by using the image obtained by the imaging. An information acquisition method including the detection of the direction of the rotation axis and the calculation of the rotation information of the rotation axis is provided.

It is a figure which shows an example of the encoder device which concerns on embodiment. (A) is a plan view of the encoder device according to the embodiment, and (B) is a diagram showing a mark portion according to the embodiment. It is a figure which shows an example of the image of the mark which is imaged by the image pickup part which concerns on embodiment. It is a figure which shows an example of the calculation processing of rotation information by the image processing unit which concerns on embodiment. It is a figure which shows another example of the calculation processing of rotation information by the image processing unit which concerns on embodiment. It is a figure which shows an example of the image of the mark which has different rotation positions which concerns on embodiment. It is a flowchart which shows an example of the operation of the encoder device which concerns on embodiment. It is a flowchart which shows the other example of the operation of the encoder device which concerns on embodiment. It is a flowchart which shows the other example of the operation of the encoder device which concerns on embodiment. (A) and (B) are diagrams showing marks related to modified examples. (A) and (B) are diagrams showing marks related to modified examples. (A) and (B) are diagrams showing marks related to modified examples. (A) and (B) are views which show the mark part which concerns on the modification. It is a figure which shows the mark which concerns on the modification. (A) is a diagram showing an encoder device according to a modified example, and (B) is a diagram showing an example of an image of a mark captured by an imaging unit according to an embodiment. It is a figure which shows the encoder device which concerns on the modification. It is a figure which shows the encoder device which concerns on the modification. It is a figure which shows an example of the drive device which concerns on embodiment. It is a figure which shows an example of the stage apparatus which concerns on embodiment. It is a figure which shows an example of the robot apparatus which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to this. In addition, in order to explain the embodiment, the drawings are expressed by changing the scale as appropriate, such as drawing a part in a large or emphasized manner. In addition, the directions will be described using the XYZ coordinate systems shown in the following figures as appropriate. In each of the X direction, the Y direction, and the Z direction, it is assumed that the direction of the arrow in the figure is the + direction (eg, the + X direction) and the opposite direction is the − direction (−X direction).

FIG. 1 is a diagram showing an example of an encoder device EC according to an embodiment. The encoder device EC images the mark 4 whose direction (for example, the direction on the surface intersecting the rotation axis 3) changes due to the rotation of the rotation axis 3 of the drive unit 2. Further, the encoder device EC calculates the rotation information of the rotation axis 3 by using the image obtained by imaging the mark 4. The encoder device EC includes a mark unit 5, an illumination unit 6, an image pickup unit 7, and an image processing unit 8. The storage unit 9 may be provided in the encoder device EC, or may be provided outside the device (eg, an external device) of the encoder device EC. In this case, the image processing unit 8 and the external storage unit 9 are configured so that signals, data, and the like can be communicated wirelessly or by wire. Further, the relative positions of the mark 4 and the imaging unit 7 may change as the rotation axis rotates. For example, the mark 4 is fixed to the non-rotating portion, and the imaging unit 7 may change as the rotation shaft 3 rotates. May rotate.

The drive unit 2 rotationally drives the rotary shaft 3. The drive unit 2 is, for example, a part of the drive device MTR shown later in FIG. The drive unit 2 is, for example, an electric motor, but may not be an electric motor. The drive unit 2 may be a device having a shaft unit that rotates using hydraulic pressure or pneumatic pressure. The rotating shaft 3 is rotated by the driving force (torque) of the driving unit 2. The rotating shaft 3 is a shaft (rotor) of the drive unit 2, but may be a shaft connected to the shaft of the drive unit 2. The rotary shaft 3 may be a shaft in a power transmission unit such as a transmission connected to the shaft of the drive unit 2. The rotary shaft 3 may be a shaft connected to the shaft of the drive unit 2 via a power transmission unit. The rotating shaft 3 may be a shaft connected to a load.

As an example, the mark 4 is formed on the mark portion 5 provided at the end portion of the rotating shaft 3. The end portion of the rotating shaft 3 refers to the end face of the rotating shaft 3 and its vicinity. The mark portion 5 may be a part of the rotating shaft 3 or may be another member attached to the end portion of the rotating shaft 3. When the mark portion 5 is a part of the rotating shaft 3, the mark portion 5 is at or near the end face of the rotating shaft 3, and the mark 4 is built in the rotating shaft 3.
When the mark portion 5 is provided as a member separate from the rotating shaft 3, for example, the mark portion 5 can be attached to the end surface of the rotating shaft 3.
The mark portion 5 is provided at the end portion of the rotating shaft 3 on the opposite side (anti-output shaft side) of the side connected to the load 11. When the mark portion 5 is provided on the counter-output shaft side, dirt (eg, oil, oil mist, etc.) from the load 11 or the like is suppressed from adhering to the mark portion 5. The mark portion 5 rotates according to the rotation direction and rotation angle of the rotation shaft 3. The mark portion 5 rotates integrally with the rotation shaft 3.

FIG. 2A is a plan view of the encoder device EC as viewed from the + Z direction, and FIG. 2B is a diagram showing a mark portion 5. A mark 4 whose direction is changed by the rotation of the rotation shaft 3 is formed on the mark portion 5. The mark 4 is a pattern capable of indicating the rotation position of the mark portion 3. The orientation (eg, direction) of the mark 4 on the plane intersecting (eg, orthogonal, non-orthogonal) with the rotating shaft 3 changes due to the rotation of the rotating shaft 3. The mark 4 includes at least one line (eg, a plurality of lines 12). The mark 4 includes, for example, at least one of a straight line (a straight line, the shortest line connecting two points, a line segment) and a curve. The line of the mark 4 is, for example, a strip having a finite width in the length direction. Hereinafter, a strip-shaped figure having a finite width is referred to as a line (eg, a straight line, a curve, a line segment) for convenience. At least one line of the mark 4 may be a line including a linear portion and a curved portion. At least one line of the mark 4 may be a line including a polygonal line portion, or a line including a polygonal linear portion and a curved line portion. The plurality of lines 12 are, for example, line segments, and are arranged in parallel with each other. The plurality of lines 12 may be formed with reference to the rotation axis 3. For example, at least one of the plurality of lines 12 may be formed so as to pass through the center of the rotating shaft 3, and none of the plurality of lines 12 may pass through the center of the rotating shaft 3. The plurality of lines 12 are arranged parallel to each other in a predetermined direction (eg, X direction), and are arranged apart from each other in an intersecting direction (eg, Y direction, orthogonal direction, non-orthogonal direction) in a predetermined direction. When one of the plurality of lines 12 is used as the reference line, the remaining lines have a predetermined distance from the reference line. The number of lines 12 is set to an arbitrary number. Each of the plurality of lines 12 may be a line segment connecting two points on the outer circumference of the end surface 10 of the rotating shaft 3. The plurality of lines 12 may be arranged in an intersecting direction (Y direction) with respect to at least one of the lines 12. The plurality of lines 12 may be arranged at equal intervals, or may be arranged at different intervals. The distance d between the plurality of lines 12 is arbitrarily set. Although FIG. 2B shows an example in which the plurality of lines 12 are arranged at positions that do not pass through the rotation center O, at least one of the plurality of lines 12 is arranged at a position that passes through the rotation center O of the rotation axis 3. May be done. The number of lines 12 included in the mark 4 is arbitrary, and may be one or a plurality. The length of the lines included in the mark 4 is also arbitrary, and when there are a plurality of lines, they may all have the same length or may have different lengths. For example, when the mark portion is circular, the length of at least one line may be longer than the radius of the mark portion.

The mark 4 may be non-axisymmetric with respect to at least one straight line passing through the rotation center O of the rotation axis 3. Further, the mark 4 may be non-axisymmetric with respect to all straight lines passing through the rotation center O of the rotation axis 3. For example, the mark 4 includes the figure 14, and the figure 14 and the plurality of lines 12 can be combined to be non-axisymmetric with respect to any straight line passing through the rotation center O of the rotation axis 3. The figure 14 may be provided in only one of the two regions R1 formed by dividing the mark portion 5 by a straight line (for example, the straight line L1) passing through the rotation center O of the rotation axis 3 (eg, only the region R1 in the −X direction). good. The area where the figure 14 is provided and the area where the figure 14 is not provided may be located point-symmetrically with respect to the center of the rotation axis. Further, the area where the figure 14 is provided and the area where the figure 14 is not provided may be provided line-symmetrically with respect to the straight line L1 passing through the rotation center O of the rotation axis 3. The figure 14, which will be described later with reference to FIG. 6, can be used to distinguish the rotation (polarity) of 180 °. The figure 14 has, for example, a shape different from any of the plurality of lines 12. The figure 14 has, for example, a bow shape including a part of the outer circumference of the end face 10 in the −X direction. For example, the figure 14 has a spread in the rotation direction (circumferential direction) of the rotation axis 3 in the central axis direction view of the rotation axis 3 (state in which the mark 4 is viewed in a plane). In FIG. 2B, one line arbitrarily selected from the plurality of lines 12 in the central axis direction view of the rotation axis 3 is defined as the reference line 12x. The angle between the straight line OE1 connecting the one end E1 of the figure 14 in the rotation direction of the rotation axis 3 and the rotation center O of the rotation axis 3 and the reference line 12x is γ1, and the other end E2 of the figure 14 in the rotation direction of the rotation axis 3 is defined as γ1. When the angle between the straight line OE2 connecting the rotation axis 3 and the rotation center O of the rotation axis 3 and the reference line 12x is γ2, γ1 and γ2 have a relationship of 0 ° <γ1 <180 ° and 0 ° <γ2 <180 °. One or both of the relationships may be satisfied.

The mark 4 is formed so as to be identifiable (distinguishable from other parts) on the image captured by the imaging unit 7. For example, the line of the mark 4 is, for example, a marking line formed (engraved) on the end face 10. The line 12 of the mark 4 may be, for example, a groove, a recess or a concave portion formed on the end face 10, or the line 12 of the mark 4 may be a convex portion or a structure. When the plurality of lines 12 are marking lines formed on the end face 10, at least one of the plurality of lines 12 may have a different line depth from the other lines 12, and the other lines 12 may be different in depth. And the line thickness may be different. The figure 14 of the mark 4 is, for example, a roughened surface of the end face 10. The mark portion 5 is, for example, a part of the rotating shaft 3, but may be a member attached to the rotating shaft 3 (a member different from the rotating shaft 3) (described later in FIG. 13B). The mark 4 may be formed on the end face 10 by printing or the like, or a part of the end face 10 may be subjected to surface treatment such as blackening. Further, the mark 4 may be surface-treated so that the reflectance of light in a part of the end face 10 is higher than that in the other part. The mark 4 may be formed over the entire area (eg, the entire surface) of the mark portion 5 (eg, the end face 10), or may be formed only on a part of the mark portion 5 (eg, the end face 10).

Returning to the description of FIG. 1, the illuminating unit 6 illuminates the mark 4. For example, the illumination unit 6 is arranged in the vicinity of the mark unit 5 and irradiates the mark 4 with light. The illumination unit 6 includes, for example, a solid-state light source such as a chip-type light emitting diode (LED). The illumination unit 6 may include a solid-state light source (eg, a laser diode) other than the light emitting diode, or may include a lamp light source.

The imaging unit 7 images the mark 4. The imaging unit 7 is arranged in the vicinity of the mark unit 5, for example. The imaging unit 7 images the mark 4 from, for example, the normal direction (eg, the Z direction) of the end face 10. The image pickup unit 7 may take an image of the mark 4 while the mark 4 is illuminated by the illumination unit 6. The image pickup unit 7 includes, for example, an imaging optical system 17 and an image pickup device 18. The imaging optical system 17 has a lens and forms an image of the mark 4. The image pickup device 18 captures an image formed by the imaging optical system 17. The image sensor 18 is, for example, a solid-state image sensor (two-dimensional image sensor) such as a CCD image sensor or a CMOS image sensor. The imaging optical system 17 includes, for example, an autofocus mechanism, and the imaging element 18 images the mark 4 in a state where the focal position of the imaging optical system 17 is in focus on the mark 4. The imaging unit 7 generates an captured image of the mark 4.

FIG. 3 is a diagram showing an example of an image Im (captured image) captured by the imaging unit 7. The imaging unit 7 images the entire area of the mark 4 formed on the mark unit 5, for example. That is, the field of view of the imaging unit 7 may be preset in a range including the entire area of the mark 4. Further, the field of view of the imaging unit 7 may be set so that the portion other than the mark 4 in the image Im is reduced when the entire area of the mark 4 is imaged. For example, the visual field center of the imaging unit 7 is set at or near the rotation center O of the rotation axis 3. The imaging unit 7 does not have to image the entire area of the mark 4, and may image a part of the mark 4. Further, the imaging unit 7 captures the mark 4 in a plurality of times (eg, scans), and the image processing unit 8 uses an image obtained by synthesizing two or more of the plurality of images obtained by the plurality of imagings. , Rotation information may be calculated.

Returning to the description of FIG. 1, the imaging unit 7 is connected to the image processing unit 8 by wire or wirelessly, and supplies (eg, transmits) the image Im data of the captured mark 4 to the image processing unit 8. The image processing unit 8 processes the image Im (see FIG. 3) captured by the image pickup unit 7. The image processing unit 8 includes, for example, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and the like. The storage unit 9 is connected to, for example, an image processing unit 8 and stores various data. In the storage unit 9, the data of the image Im captured by the image pickup unit 7, the data being processed by the image processing unit 8, the data after the processing of the image processing unit 8, and the data used by the image processing unit 8 for processing (eg, setting). Values, parameters) etc. are stored. The storage unit 9 includes, for example, a RAM, a flash memory, a ROM, and the like.

The image processing unit 8 calculates the rotation information of the rotation axis 3 using the image obtained by the image pickup unit 7. For example, the image processing unit 8 detects, determines, or derives the direction of the mark 4 using the image Im captured by the image pickup unit 7, and calculates the rotation information of the rotation axis 3. The image processing unit 8 detects the rotation information of the rotation axis 3 based on the plurality of lines 12 shown in the image Im. The rotation information is information regarding the rotation of the rotation shaft 3, and includes, for example, at least one of the rotation position (angle position) of the rotation shaft 3, the amount of change in the rotation position, the angular velocity, and the angular acceleration. The rotation position of the rotation shaft 3 may be the rotation angle from the reference position. The rotation information may be information that does not distinguish the number of rotations (hereinafter, referred to as single rotation information) or information that distinguishes the number of rotations (hereinafter, referred to as multi-rotation information). For example, when the amount of change in the rotation position is 400 °, the single rotation information is represented by a value of 40 ° ignoring the number of rotations (1 rotation, 360 °), and when the amount of change in the rotation position is 40 °. It is represented by the same value. Further, the multi-rotation information is represented by a value of 400 ° or one rotation and 40 ° when, for example, the amount of change in the rotation position is 400 °. The rotation information is represented by, for example, a binary number having a predetermined number of bits, and may be a value converted into degrees (deg) or a value converted into radians (rad).

Next, the calculation process of the rotation information by the image processing unit 8 will be described. FIG. 4 is a diagram showing an example of rotation information calculation processing by the image processing unit 8. The image processing unit 8 has, for example, rotation information of the rotation axis 3 based on the number of intersections P1 between a predetermined line segment 20 provided on the image Im by image processing and images of a plurality of lines 12 on the image Im. Is calculated. For example, the image processing unit 8 binarizes the image Im captured by the imaging unit 7 and extracts a plurality of lines 12 from the binarized image by processing such as edge detection and Hough transform. The image processing unit 8 represents, for example, the extracted plurality of lines 12 by a linear expression showing the relationship between the coordinates in the horizontal scanning direction and the coordinates in the vertical scanning direction on the image Im. Subsequently, the image processing unit 8 calculates the number of intersections P1 between the predetermined line segment 20 on the image Im and the plurality of lines 12. Here, the predetermined line segment 20 will be described as being parallel to the horizontal scanning direction, but the predetermined line segment 20 may be non-parallel to the horizontal scanning line, may be parallel to the vertical scanning line, and may be horizontally scanned. It may be non-parallel to both the line and the vertical scanning line. The length L of the predetermined line segment 20 is arbitrarily set, and is, for example, arranged from the line 12a arranged at one end to the other end in the arrangement direction of the plurality of lines 12 (eg, the direction perpendicular to the line 12). The width is set to B or more up to the line segment 12b.

The coordinates of the intersection P1 on the image Im can be obtained, for example, by solving a simultaneous equation of a linear equation representing the image of the line 12 on the image Im and a linear equation representing a predetermined line segment 20. Further, the number of intersection points P1 is obtained by determining whether or not each of the plurality of lines 12 has a predetermined line segment 20 and intersection points P1 within the range of the mark 4, and counting the number of intersection points P1. .. Here, the angle between the predetermined line segment 20 shown in FIG. 4 and one line 12c of the plurality of lines 12 is φ, the distance between the plurality of lines 12 is d, and the distance between the intersection P1 and the intersection P1 is set. Assuming X, these relationships are expressed by the following equation (1). In the equation (1), || represents an absolute value.
X = | d / sinφ | ・ ・ ・ (1)

Further, the number N of the intersection points P1 is, for example, the following equation, where the integer part of L / X (the number of intervals of the lines 12 that fit in the section of the predetermined line 20 of the length L) is INT (L / X). It is represented by (2). By substituting N, d, and L into the equation (2), the angle φ between the predetermined line segment 20 and the plurality of lines 12 can be calculated.
N = INT (L / X) +1 = INT (| Lsinφ | / d) +1 ... (2)
For example, when N = 100, L / X is 99 or more and less than 100, and the image processing unit 8 can calculate the angle φ with the intermediate value 99.5 as the value of L / X. The angle φ is information indicating the directions of the plurality of lines 12 (marks 4). In this way, the image processing unit 8 detects the direction of the mark 4 by calculating the angle φ based on the plurality of lines 12, and calculates the rotation information of the rotation axis 3.

FIG. 5 is a diagram showing another example of rotation information calculation processing by the image processing unit 8. When the plurality of lines 12 at the mark 4 are arranged in parallel with each other, the image processing unit 8 may use, for example, a predetermined line segment 21 provided on the image Im and an image of the plurality of lines 12 on the image Im. Angles θ1 to θ9 are obtained, and rotation information is calculated based on the average value θm of the angles. For example, the image processing unit 8 binarizes the image of the mark 4 to extract a plurality of lines 12 and extracts the extracted plurality of lines 12 on the image Im, respectively, as described with reference to FIG. Expressed as a linear expression of coordinates. The predetermined line segment 21 is set, for example, parallel to the horizontal scanning direction on the image Im. In this case, θ1 to θ9 can be calculated from the slope of the linear expression representing each of the plurality of lines 12. The image processing unit 8 calculates, for example, the average value θm of the angles θ1 to θ9 as rotation information of the rotation axis 3. The average value θm may be, for example, an arithmetic mean, a geometric mean, or a weighted average (weighted average). The detection accuracy of the angles θ1 to θ9 is generally higher for the longer line 12 among the plurality of lines 12, and the weighting coefficient of the weighted average may be an amount proportional to the length of the line 12. In this way, the image processing unit 8 may detect the direction of the mark 4 and calculate the rotation information of the rotation axis 3 by calculating the angle θm based on the plurality of lines 12. In this way, when averaging the angles (eg, angles θ1 to θ9) between the respective images of the plurality of lines 12 and the predetermined line segments 21 provided on the image, for example, the mark 4 (eg, end face 10) is used. ) Can be reduced from the effects of dirt and scratches, and rotation information can be acquired with high accuracy. If dirt or scratches are present on the mark portion, they may be removed as noise in the processing portion in advance. If a part of the line segment has dirt or scratches, the line segment may not be used for angle detection, and information on the part with dirt or scratches may be interpolated.

The rotation information calculation process by the image processing unit 8 is not limited to the examples of FIGS. 4 and 5. For example, the image processing unit 8 may acquire the shape information (eg, reference information) of the mark 4 from the storage unit 9, and calculate the rotation information from the shape information and the image of the mark 4 on the image Im. The shape information can be, for example, an image created in advance when the rotation axis 3 is at a predetermined rotation position. For example, the shape information may be image data of the mark 4 for each predetermined angle from 0 degree to 360 degrees. This image data may be an image captured by the imaging unit 7, or may be a processed version of this image. Further, the image data may be image data acquired without using the image pickup unit 7, or may be image data generated by, for example, image creation software. For example, the image processing unit 8 can calculate the correlation between the image Im of the mark 4 captured by the image pickup unit 7 and the shape information such as the above-mentioned image data, and calculate the rotation information of the rotation axis from the image Im. can.

Further, the image processing unit 8 acquires the image Im of the mark 4 and the above-mentioned shape information (eg, image data) corresponding to each rotation position from the storage unit 9, and compares the image Im with the shape information. The rotation information may be calculated. For example, the image processing unit 8 calculates the correlation coefficient between the shape information and the image Im corresponding to each rotation position, and sets the rotation position corresponding to the shape information having the maximum correlation coefficient as the rotation position of the rotation axis 3. May be. Further, the image processing unit 8 may calculate the rotation position of the rotation axis 3 by using the correlation coefficient between the shape information corresponding to each rotation position and the image Im. For example, the image processing unit 8 first calculates the correlation coefficient using the image data for each predetermined angle as the shape information corresponding to each rotation position, and then selects the top two image data having the high correlation coefficient. The position in the section of the corresponding rotation position section may be calculated using the correlation coefficient.

Further, the image processing unit 8 may calculate the above-mentioned correlation coefficient step by step. For example, the image processing unit 8 first calculates the correlation coefficient using a plurality of image data having a coarse angle step width as shape information corresponding to each rotation position, and then the top two having a high correlation coefficient. For the section of the rotation position corresponding to the image data, the rotation position of the rotation axis 3 may be calculated by using a plurality of image data having a fine angle step size.

Further, the image processing unit 8 may calculate the rotation position of the rotation axis 3 by pattern matching the shape information corresponding to each rotation position and the image Im. For example, the image processing unit 8 first performs pattern matching using image data for each predetermined angle as shape information corresponding to each rotation position, and determines the rotation position corresponding to the shape information that maximizes the pattern matching. It may be the rotation position of the rotation shaft 3. The comparison between the image Im and the image data (eg, calculation of the correlation coefficient, pattern matching) may be performed on the entire mark 4 or on a part of the mark 4. For example, the comparison between the image Im and the image data may be performed on all of the plurality of lines 12 at the mark 4, or may be performed on a part of the plurality of lines 12.

The image processing unit 8 may calculate information other than the rotation position of the rotation shaft 3 as rotation information, or may not calculate the rotation position of the rotation shaft 3. For example, the image processing unit 8 provides rotation information such as the number of rotations, the amount of change in the rotation position, the direction of rotation, the rotation speed (eg, angular speed), the rotation acceleration (eg, angular acceleration), and the eccentric information of the rotation axis 3 (eg, angular acceleration). At least one of eccentricity error and eccentricity angle) may be calculated. For example, the image processing unit 8 may calculate the rotation direction by calculating the amount of change in the rotation position and determining the positive or negative (direction in which the position of the rotation axis 3 changes). Further, the image processing unit 8 may calculate the number of rotations in consideration of the rotation direction by integrating the amount of change in the rotation position that distinguishes the rotation directions. For example, the image processing unit 8 counts the number of rotations by +1 when the integrated value of the amount of change in the rotation position of the rotation shaft 3 exceeds 360 °, and counts the number of rotations by -1 when it falls below -360 °. Therefore, the number of rotations can be calculated. Further, the image processing unit 8 can calculate the multi-rotation information of the rotation shaft 3 by using, for example, the information of the rotation speed and the rotation direction. Further, the image processing unit 8 detects, for example, the rotation center O of the image Im of the mark 4 at each time, detects the locus of the rotation center O, and uses the detected locus data of the rotation center O to rotate the axis 3 The eccentricity of may be calculated.

Next, the polarity determination of rotation will be described. In general, it is difficult for the encoder device to distinguish between a state in which the amount of change in the rotation position is 0 ° and a state in which the amount of change in the rotation position is 180 °. For example, when the sampling frequency is smaller than the frequency at which the rotation axis rotates 180 °, it may not be possible to distinguish between a state in which the amount of change in the rotation position is 0 ° and a state in which the rotation position is 180 °.

As shown in FIG. 2, the encoder device EC according to the present embodiment has a shape in which the mark 4 is non-axisymmetric with respect to the straight line L1 passing through the rotation center O, and the amount of change in the rotation position is utilized by utilizing this asymmetry. Distinguish between the state where is 0 ° and the state where is 180 ° (polarity discrimination). For example, the mark 4 is non-axisymmetric with respect to the straight line L1 because the figure 14 is provided only on one of the pair of regions R1 sandwiching the straight line L1 passing through the center of rotation.

FIG. 6 is a diagram showing an image Im of the mark 4 captured by the imaging unit 7 in association with the rotation position of the rotation axis 3. For example, the imaging unit 7 images the mark unit 5 at a predetermined interval (eg, sampling cycle) while the rotation shaft 3 is rotating. FIG. 6 shows an image captured by the imaging unit 7 of marks 4 at rotation positions of the rotation axis 3 at 0 °, 45 °, 90 °, 135 °, 280 °, 225 °, 270 °, 315 °, and 360 °. Im was shown. Here, for convenience of explanation, the case where the plurality of lines 12 of the mark 4 are parallel to the X direction (horizontal scanning direction) is defined as the reference of the rotation position of the rotation axis 3 (eg, 0 °).

The image processing unit 8 distinguishes between a state in which the rotation position is α ° and a state in which the rotation position is (α + 180) °, for example, by detecting the figure 14. For example, in the image processing unit 8, when the angle between the plurality of lines 12 and the horizontal scanning line of the image Im is 0 ° (rotation position is 0 °, 180 °), the figure 14 on the image Im has the rotation center O. It is determined which side is on the line Cy that passes through and is parallel to the vertical scanning line. For example, the image processing unit 8 determines that the rotation position is 0 ° when the figure 14 is on the left side of the line Cy, and determines that the rotation position is 180 ° when the figure 14 is on the right side of the line Cy. do. Further, for example, in the image processing unit 8, when the angle between the plurality of lines 12 and the horizontal scanning line of the image Im is 90 ° (rotation position is 90 °, 270 °), the figure 14 on the image Im is rotated. It is determined which side is on the line Cx passing through the center O and parallel to the horizontal scanning line. For example, the image processing unit 8 determines that the rotation position is 90 ° when the figure 14 is above the line Cx, and determines that the rotation position is 270 ° when the figure 14 is below the line Cx. judge.

The image processing unit 8 determines the polarity by determining which of the first to fourth quadrants the figure 14 is located in, for example, in the Cartesian coordinate system with the rotation center O as the origin on the image Im. You may go. As described above, when the figure 14 is used for the polarity determination, if the figure 14 and the plurality of lines 12 have different shapes, it is easy to distinguish the figure 14 from the plurality of lines 12. Further, the polarity may be determined without using the figure 14 (described later in FIG. 10 and the like), and in this case, the mark 4 may not include the figure 14. Further, the encoder device EC may perform polarity determination without using the mark 4. For example, the encoder device EC may set the sampling frequency smaller than the frequency at which the rotating shaft 3 rotates 180 °, and may integrate the amount of change in the rotating position of the rotating shaft 3 to determine the polarity. Further, the encoder device EC may perform polarity determination by a magnetic encoder (later shown in FIG. 16), a double encoder (later shown in FIG. 17), or the like.

The image processing unit 8 outputs the rotation information of the rotation shaft 3 calculated as described above to the outside. The image processing unit 8 transmits rotation information to the outside by high-speed bidirectional serial communication, for example. For example, the image processing unit 8 outputs the rotation information of the rotation shaft 3 to a control unit (eg, a control unit 34 shown later in FIG. 18) that controls the drive unit 2. The control unit 34 can accurately control the drive unit 2 by using the rotation information of the rotation shaft 3.

Next, an information acquisition method will be described based on the operation of the encoder device EC as described above. FIG. 7 is a flowchart showing an example of the operation of the encoder device EC. In step S1, the imaging unit 7 images a mark 4 provided on the rotating shaft 3 of the driving unit 2 and including a plurality of lines 12 whose orientation changes due to the rotation of the rotating shaft 3. In step S2, the image processing unit 8 detects the orientation of the mark 4 using the captured image and calculates the rotation information of the rotation axis 3. For example, the image processing unit 8 detects the position information of the rotation axis based on the plurality of lines 12. In step S3, the image processing unit 8 outputs the calculated rotation information to the outside. It is optional whether or not step S3 is performed.

FIG. 8 is a flowchart showing an example of the rotation information calculation process shown in step S2 of FIG. In this example, the image processing unit 8 has the rotation axis 3 based on the number of intersections P1 between the predetermined line segment 20 provided on the image Im and the images of the plurality of lines 12 as described with reference to FIG. Calculate rotation information. In step S10, the image processing unit 8 extracts a plurality of lines 12 from the image captured by the imaging unit 7 (eg, the image Im in FIG. 4). In step S11, the image processing unit 8 calculates the number of intersections P1 between the predetermined line segment 20 provided on the image Im and the images of the plurality of lines 12. In step S12, the image processing unit 8 calculates the rotation information of the rotation axis 3 based on the number of intersections P1.

FIG. 9 is a flowchart showing another example of the rotation information calculation process shown in step S2 of FIG. In this example, the image processing unit 8 calculates the angles θ1 to θ9 between the predetermined line segment 20 provided on the image Im and the images of the plurality of lines 12 as described with reference to FIG. 5, and averages the angles. Rotation information is calculated based on the value θm. In step S10, the image processing unit 8 extracts a plurality of lines 12. In step S13, the image processing unit 8 calculates the angles θ1 to θ9 between the line 12 on the image Im and the predetermined 20 for each of the plurality of lines 12. In step S14, the image processing unit 8 calculates an average value θm of the images and angles of the predetermined line segment 20 and the plurality of lines 12 provided on the image Im. Further, the image processing unit 8 calculates the rotation information of the rotation axis 3 based on the average value θm of the angles.

As described above, the encoder device EC according to the present embodiment detects the direction of the mark 4 using the image obtained by capturing the mark 4, and calculates the rotation information of the rotation axis 3. The mark 4 can be easily formed as a marking line or the like as described above. Further, even when the mark 4 (eg, a plurality of lines 12) deviates from the rotation center O of the rotation shaft 3, the rotation information can be calculated accurately. Further, in a normal encoder device, the scale is provided only in a part near the outer periphery of the rotating plate, and the reading accuracy of the scale may be lowered due to the miniaturization of the scale. Since the encoder device EC according to the present embodiment calculates the rotation information of the rotation shaft 3 according to the direction of the mark 4, for example, the line 12 can be arranged over a wide range of the end face 10 of the rotation shaft 3, and has a simple configuration. As a result, it is possible to suppress a decrease in the detection accuracy of the wire 12 while reducing the size of the encoder device EC (mark 4).

The encoder device EC may calculate rotation information other than the rotation position. For example, the encoder device EC may calculate at least one of the amount of change in the rotation position of the rotation shaft 3, the angular velocity, and the angular acceleration as rotation information. Further, the encoder device EC does not have to calculate the rotation position of the rotation shaft 3 as the rotation information.

[Modification example]
Next, a modified example will be described. In this modification, the elements corresponding to the above embodiments are designated by the same reference numerals, and the description thereof will be omitted or simplified. FIG. 10A is a diagram showing the mark 4 according to the first modification. In the first modification, the mark 4 does not include the figure 14. The mark 4 lacks one end of the line 12d among the plurality of lines 12. As a result, the mark 4 has a non-axisymmetric shape with respect to the straight line L1 in which the plurality of lines 12 are perpendicular to the predetermined direction (X direction) and pass through the rotation center O of the rotation axis 3. Further, the mark 4 is non-axisymmetric with respect to at least one straight line passing through the center of the mark portion 5. Even if such a mark 4 is used, the image processing unit 8 can discriminate (polarize) between a state in which the amount of change in the rotation position is 0 ° and a state in which the change amount is 180 °.

FIG. 10B is a diagram showing the mark 4 according to the second modification. In the second modification, the mark 4 has a distance d between the line 12 and the line 12 in a part of the plurality of lines 12, and the line 12e and the line 12e in the other part (-Y side). The interval between is d1. d1 is set to a value different from d. In this way, the intervals between the plurality of lines 12 do not have to be equal. That is, the density of the plurality of lines 12 does not have to be constant. By arranging the plurality of lines 12 in this way, the mark 4 has a shape that is parallel to the plurality of lines 12 (parallel to the X direction) and non-axisymmetric with respect to the straight line L2 passing through the rotation center O of the rotation axis 3. It has become. In the mark 4 of FIG. 10 (B), the lines 12e are densely arranged on the −Y side, and the lines 12e are arranged on the + Y side in a state rotated by 180 ° from the state of FIG. 10 (B). Even if such a mark 4 is used, the image processing unit 8 can discriminate (polarize) between a state in which the amount of change in the rotation position is 0 ° and a state in which the change amount is 180 °. Further, when at least one of the plurality of lines 12 is formed with a thickness different from that of the other lines 12, or when the lines 12 are formed as grooves, dents, recesses, or marking lines, the lines with the other lines 12 The image processing unit 8 can discriminate (polarize) between a state in which the amount of change in the rotation position is 0 ° and a state in which the change amount is 180 °, even if the images are formed at different depths.

FIG. 11A is a diagram showing the mark 4 according to the third modification. In the third modification, the plurality of lines 12 include a polygonal line. FIG. 11B is a diagram showing the mark 4 according to the fourth modification. In the fourth modification, the plurality of lines 12 include a curve. As in the third modification and the fourth modification, the shape of the line 12 is arbitrary and may be a shape other than a straight line (line segment). Further, the plurality of lines 12 do not have to have the same shape. For example, the plurality of lines 12 may be a combination of a line segment, a curved line, and a polygonal line. The plurality of lines 12 may have one line intersecting with another line. For example, at least one line of the plurality of lines 12 may intersect with another line at only one place, or may intersect with another line (eg, polygonal line, curve) at two or more places. Further, at least one of the plurality of lines 12 may include, for example, at least one of a polygonal line portion and a curved portion, and may intersect with itself. When the plurality of lines 12 include a polygonal line or a curved line, for example, the image processing unit 8 correlates the image Im of the mark 4 captured by the imaging unit 7 with the shape information such as a plurality of image data for each rotation position. You may calculate, detect the mark 4 from the image Im, and detect the direction of the mark 4.

FIG. 12A is a diagram showing the mark 4 according to the fifth modification. In the fifth modification, the mark 4 includes the figure 14. The figure 14 in FIG. 12A is circular, but the shape of the figure 14 is arbitrary, and may be a shape other than a circle, for example, a polygonal shape such as a triangle, an ellipse, or the like, and the outline is a line segment. It may be a shape including a curve (eg, a track shape). Further, the figure 14 may be linear, or may be a line segment, a curved line, or a shape obtained by combining at least one of a line segment and a curved line (eg, a cross shape). Further, the position of the figure 14 is arbitrary. For example, the figure 14 may be in contact with the outer circumference of the mark portion 5 as shown in FIG. 2 (B), or may be in contact with the outer periphery of the mark portion 5 as shown in this modification. It does not have to be in contact with the outer circumference. The image processing unit 8 can perform curve discrimination based on the figure 14.

FIG. 12B is a diagram showing the mark 4 according to the sixth modification. The mark 4 according to the sixth modification includes a plurality of figures 14 that are independent (discontinuous) from each other. The figure 14 includes, for example, a circular figure 14a and a rectangular figure 14b. The image processing unit 8 determines the polarity based on at least one position of the figure 14a and the figure 14b, for example. When there are a plurality of figures 14 in this way, even if one of the plurality of figures 14 becomes dirty, the polarity can be determined based on the information of the other figures. The number of figures included in the figure 14 is arbitrary, and for example, the figure 14 may include three or more figures.

FIG. 13A is a diagram showing a mark portion 5 according to the seventh modification. In the seventh modification, the mark 4 has a shape that is non-axisymmetric with respect to the straight line L1 that is perpendicular to the predetermined direction (X direction) and passes through the rotation center O of the rotation axis 3. The mark 4 of this modification has a shape in which a part of the end face 10 of the rotating shaft is cut off. A part of the end face 10 of FIG. 13A is cut out in a bow shape, but the shape to be cut out is not particularly limited. The mark 4 may have a shape in which the end face 10 itself is cut off, or a shape in which another member attached to the end face 10 as a mark portion 5 is cut off. The mark 4 includes, for example, a plurality of lines 12 parallel to the X direction. Since the cut-out portion of the mark 4 is out of the in-focus position of the imaging optical system 17, it is easy to distinguish it on the image captured by the imaging unit 7. As a result, the mark 4 has an asymmetrical shape (for example, non-axisymmetric with respect to the straight line L1), and the polarity can be determined by utilizing this asymmetry. The notch may be, for example, a V-shaped recess. When the plurality of lines 12 included in the mark 4 are grooves, dents, recesses, or marking lines, the depth of the notch may be larger than the depth of the line, and may be larger than the width of the line. The width of the notch may be larger.

FIG. 13B is a diagram showing a mark portion 5 according to the eighth modification. In the eighth modification, the mark 4 is formed on the mark portion 5 attached to the end portion of the rotating shaft 3. For example, the mark portion 5 is a disk-shaped member and is attached to the end surface 10 of the rotating shaft 3. The mark portion 5 does not have to be formed directly on the end face 10 as long as it is provided at the end of the rotating shaft 3. For example, the mark portion 5 may be detachably formed at the end portion of the rotating shaft 3. Further, the outer peripheral shape of the mark portion 5 may be a shape that is non-axisymmetric with respect to a predetermined straight line L1 passing through the rotation center O of the rotation shaft 3, as in the shape of the end face 10 of the seventh modification.

FIG. 14 is a diagram showing the mark 4 according to the ninth modification. In the ninth modification, the mark 4 is provided on a disk attached to the end of the rotating shaft 3. As described above, the mark 4 may be provided at a position other than the end surface 10 of the rotating shaft 3.

FIG. 15A is a diagram showing an encoder device EC according to a tenth modification, and FIG. 15B is a diagram showing an example of an image Im2 captured by the imaging unit 7b. In the tenth modification, the encoder device EC includes a plurality of image pickup units 7a and an image pickup unit 7b, and the mark 4 is imaged by each of the plurality of image pickup units 7a and the image pickup unit 7b. The encoder device EC includes, for example, a mark unit 5, an illumination unit 6, an image pickup unit 7a, an image pickup unit 7b, an image processing unit 8, and a storage unit 9. The mark unit 5, the illumination unit 6, the image processing unit 8, and the storage unit 9 may be the same as those in the above-described embodiment or each modification.

The imaging unit 7a images the entire area of the mark 4 formed on the mark unit 5. The field of view of the imaging unit 7a is preset, for example, in a range including the entire area of the mark 4. The imaging unit 7b images a part of the mark 4 formed on the mark unit 5. The field of view of the imaging unit 7b is set, for example, in the region R2 including only a part of the mark 4. As shown in FIG. 15B, for example, this region R2 is set to include a region R1 sandwiching a straight line L3 passing through the rotation center O of the mark 4. The imaging unit 7a and the imaging unit 7b are respectively arranged in the vicinity of the mark unit 5. The image pickup unit 7a and the image pickup unit 7b each include an imaging optical system 17 and an image pickup element 18. The image capturing unit 7a and the imaging unit 7b each output the captured image data to the image processing unit 8. The image processing unit 8 determines the polarity using, for example, the image Im2 including only a part of the mark 4, and calculates the rotation information of the rotation axis 3. The image processing unit 8 determines the polarity, for example, by detecting the figure 14 included in the image Im2.

In this way, the encoder device EC may image the mark 4 by a plurality of imaging units (imaging unit 7a and imaging unit 7b) and detect the rotation information of the rotation axis 3. The imaging unit 7b may image the entire area of the mark 4. For example, the encoder device EC may use the rotation information obtained from the image captured by the imaging unit 7b for interpolation, verification, backup, and the like of the rotation information obtained from the image captured by the imaging unit 7a. Further, the number of the imaging units 7 may be three or more. By the way, the image used for the polarity determination may have a lower resolution than the image used for detecting the rotation position. For example, the polarity can be determined by using a photodetector that detects the brightness of a part of the region through which the figure 14 passes by rotating the rotation axis 3. For example, the encoder device EC may include the above-mentioned photodetector instead of the imaging unit 7b.

FIG. 16 is a diagram showing an encoder device EC according to the eleventh modification. In the eleventh modification, the encoder device EC detects the multi-rotation information by using a processing unit different from the image processing unit 8. The encoder device EC includes, for example, a mark unit 5, an illumination unit 6, an image pickup unit 7, an image processing unit 8, a storage unit 9, and a magnetic encoder unit 25. The mark unit 5, the illumination unit 6, the image pickup unit 7, the image processing unit 8, and the storage unit 9 may be the same as those of the above-described embodiment or each modification.

The magnetic encoder unit 25 detects the rotation speed and the rotation direction of the rotation shaft 3. The magnetic encoder unit 25 includes, for example, a magnet 26, a magnetic sensor 27, and a signal processing unit 28. The magnet 26 is provided on a disk 29 fixed to the rotating shaft 3. Since the disk 29 rotates together with the rotating shaft 3, the magnet 26 rotates with the rotation of the rotating shaft 3 (accompanied by the rotating shaft 3). The magnetic sensor 27 includes, for example, a Hall element, and detects a change in the magnetic field that accompanies the rotation of the magnet 26. The signal processing unit 28 detects the rotation speed and the rotation direction of the rotation shaft 3 by using the detection result of the magnetic sensor 27. The signal processing unit 28 outputs the detected rotation speed and rotation direction of the rotation shaft 3 to the image processing unit 8. The image processing unit 8 uses the rotation speed and rotation direction of the rotation shaft 3 detected by the signal processing unit 28 and the rotation position of the rotation shaft 3 obtained from the image captured by the image pickup unit 7 (for example, by synthesizing them). ), Calculate the multi-rotation information of the rotation shaft 3. Here, the image processing unit 8 synthesizes the rotation information (eg, rotation position) obtained from the image captured by the image pickup unit 7 and the rotation information (eg, rotation number and rotation direction) detected by the signal processing unit 28. Although it also serves as a compositing unit, the compositing unit may be provided separately from the image processing unit 8. As described above, the encoder device EC may detect the multi-rotation information by using a processing unit different from the image processing unit 8, or may detect the multi-rotation information by using the image processing unit and another processing unit in combination. You may. The processing unit that detects the multi-rotation information does not have to be the magnetic encoder unit 25, and may be, for example, an optical rotary encoder.

FIG. 17 is a diagram showing an encoder device EC according to a twelfth modification. In the twelfth modification, the encoder device EC is a double encoder. The encoder device EC detects the rotation information of the rotating shaft 3 and the rotation information of the shaft whose rotation is adjusted with respect to the rotating shaft 3. The encoder device EC includes, for example, a mark unit 5, an illumination unit 6, an image pickup unit 7, an image processing unit 8, a storage unit 9, and an encoder unit 32. The mark unit 5, the illumination unit 6, the image pickup unit 7, the image processing unit 8, and the storage unit 9 may be the same as those of the above-described embodiment or each modification.

The encoder unit 32 is arranged in the vicinity of a shaft (not shown) whose rotation is adjusted by the transmission 31, and detects rotation information of this shaft. The encoder unit 32 may, for example, detect the direction of the mark as in the above-described embodiment, may be a rotary encoder using a scale, or may be a magnetic encoder or the like. The encoder unit 32 outputs, for example, the detected rotation information to the image processing unit 8. The image processing unit 8 calculates the multi-rotation information of the rotation shaft 3 by using the rotation information detected by the encoder unit 32 and the rotation position of the rotation shaft 3 detected by the image processing unit 8. The encoder device EC may perform polarity determination using the rotation information detected by the encoder unit 32, and in this case, the image processing unit 8 does not perform polarity determination using the image captured by the image pickup unit 7. You may.

The mark 4 does not have to be provided in the encoder device EC. For example, the mark 4 may be retrofitted to the rotating shaft 3. Further, the illumination unit 6 does not have to be provided in the encoder device EC. For example, the illumination unit 6 may be retrofitted, or the image pickup unit 7 may capture a mark illuminated by light from an interior light, natural light, or the like.

The predetermined line segment 20 or the predetermined line segment 21 shown in FIGS. 5 and 6 does not have to be parallel to the horizontal scanning direction in the image Im. For example, the predetermined line segment 20 or the predetermined line segment 21 may be inclined at an arbitrary angle with respect to the vertical scanning direction in the image Im. Further, the predetermined line segment 20 or the predetermined line segment 21 does not have to be one, and the predetermined line segment 20 or the predetermined line segment 21 may be two or more.

[Drive]
Next, the drive device will be described. FIG. 18 is a diagram showing an example of the drive device MTR. In the following description, the same or equivalent components as those in the above-described embodiment are designated by the same reference numerals to omit or simplify the description. The drive device MTR is, for example, a motor device including an electric motor. The drive device MTR controls the main body (drive unit) BD by using the main body (drive unit) BD that supplies the driving force to the first axis AX1, the encoder device EC, and the rotation information calculated by the image processing unit 8. A control unit 34 for the operation is provided.

The rotating shaft SF has a load-side end SFa and a non-load-side end SFb. The load side end SFa is connected to another power transmission mechanism such as a speed reducer. The mark portion 5 on which the mark 4 is formed is provided on the counterload side end portion SFb. The encoder device EC may be any of the above-described embodiments, modifications, or a combination thereof. The encoder device EC includes, for example, an imaging unit 7 and an image processing unit 8. The imaging unit 7 images the mark 4. The image processing unit 8 detects the direction of the mark 4 using the image of the mark 4 captured by the imaging unit 7, calculates the rotation information of the rotation shaft 3, and detects the rotation position of the rotation shaft 3. The image processing unit 8 is connected to the control unit 34 and outputs the detection result to the control unit 34.

In this drive device MTR, the control unit 34 controls the main body unit (drive unit) BD by using the detection result of the encoder device EC. Since the encoder device EC can accurately detect the rotation information of the rotation shaft 3, the drive device MTR can operate with high accuracy. The drive device MTR is not limited to the drive device, and may be another drive device having a shaft portion that rotates using hydraulic pressure or pneumatic pressure.

[Stage device]
Next, the stage device will be described. FIG. 19 is a diagram showing a stage device STG. This stage device STG has a configuration in which a rotary table (moving body) TB is attached to a load-side end SFa of the rotary shaft SF of the drive device MTR shown in FIG. In the following description, the same or equivalent components as those in the above-described embodiment are designated by the same reference numerals to omit or simplify the description.

When the stage device STG drives the drive device MTR to rotate the rotation shaft SF, this rotation is transmitted to the rotary table TB. At that time, the encoder device EC detects the angular position of the rotation axis SF and the like. Therefore, the angular position of the rotary table TB can be detected by using the output from the encoder device EC. A speed reducer or the like may be arranged between the load side end SFa of the drive device MTR and the rotary table TB.

As described above, the stage device STG can be operated accurately because the encoder device EC can accurately detect the rotation information of the rotation shaft 3. The stage device STG can be applied to, for example, a rotary table provided in a machine tool such as a lathe.

[Robot device]
Next, the robot device will be described. FIG. 20 is a perspective view showing the robot device RBT. Note that FIG. 20 schematically shows a part (joint portion) of the robot device RBT. In the following description, the same or equivalent components as those in the above-described embodiment are designated by the same reference numerals to omit or simplify the description. This robot device RBT has a first arm AR1, a second arm AR2, and a joint portion JT. The first arm AR1 is connected to the second arm AR2 via the joint JT.

The first arm AR1 includes an arm portion 101, a bearing 101a, and a bearing 101b. The second arm AR2 has an arm portion 102 and a connecting portion 102a. The connecting portion 102a is arranged between the bearing 101a and the bearing 101b in the joint portion JT. The connecting portion 102a is provided integrally with the rotating shaft SF. The rotary shaft SF is inserted into both the bearing 101a and the bearing 101b at the joint portion JT. The end of the rotating shaft SF on the side inserted into the bearing 101b penetrates the bearing 101b and is connected to the speed reducer RG.

The speed reducer RG is connected to the drive device MTR, and reduces the rotation of the drive device MTR to, for example, 1/100 or the like and transmits it to the rotation shaft SF. Although not shown in FIG. 20, the load-side end SFa of the rotation shaft SF of the drive device MTR is connected to the speed reducer RG. Further, although not shown in FIG. 20, a mark portion 5 on which the mark 4 of the encoder device EC is formed is provided on the counterload side end portion SFb of the first axis AX1 of the drive device MTR.

When the robot device RBT drives the drive device MTR to rotate the first shaft AX1, this rotation is transmitted to the rotation shaft SF via the speed reducer RG. The connection portion 102a is integrally rotated by the rotation of the rotation shaft SF, whereby the second arm AR2 is rotated with respect to the first arm AR1. At that time, the encoder device EC detects the angular position of the first axis AX1 and the like. Therefore, the angular position of the second arm AR2 can be detected by using the output from the encoder device EC.

In this way, the robot device RBT can operate with high accuracy because the encoder device EC can accurately detect the rotation information of the rotation shaft 3. The robot device RBT is not limited to the above configuration, and the drive device MTR can be applied to various robot devices having joints.

The technical scope of the present invention is not limited to the embodiments described in the above-described embodiments. One or more of the requirements described in the above embodiments and the like may be omitted. In addition, the requirements described in the above-described embodiments and the like can be combined as appropriate. In addition, to the extent permitted by law, the disclosure of all documents cited in the above-mentioned embodiments and the like shall be incorporated as part of the description in the main text.

EC ... Encoder device, 2 ... Drive unit (drive device), 3 ... Rotating shaft, 4 ... Mark, 5 ... Mark part, 7, 7a, 7b ... Imaging unit, 8 ... image processing unit, 9 ... storage unit, 10 ... end face, 12, 12a to 12e ... line, 14, 14a to 14c ... graphic, 20, 21 ... predetermined line, 34 ... Control unit, Im, Im2 ... Image, MTR ... Drive device, STG ... Stage device, RBT ... Robot device

Claims (16)

An imaging unit that captures a mark containing a line whose direction changes due to the rotation of the rotation axis,
An encoder device including a processing unit that obtains rotation information of the rotation axis based on the number of intersections of the line image obtained by the imaging unit and a predetermined line set in the image by the imaging unit. An imaging unit that captures marks containing marking lines that change direction due to the rotation of the rotation axis,
An encoder device including a processing unit that obtains rotation information of the rotation axis based on an image obtained by the imaging unit. The encoder device according to claim 1 or 2, wherein the mark is formed on a mark portion at an end portion of the rotating shaft. The encoder device according to any one of claims 1 to 3, wherein the mark is formed on a disk fixed to the rotating shaft. The encoder device according to any one of claims 1 to 4, wherein the mark includes a plurality of parallel lines. The encoder device according to claim 5, wherein the plurality of parallel lines is a plurality of parallel straight lines, a plurality of parallel curves, or a plurality of parallel polygonal lines. The encoder device according to claim 5 or 6, wherein the plurality of parallel lines are arranged at equal intervals. The encoder device according to claim 3, wherein the mark has a shape that is non-axisymmetric with respect to at least one straight line passing through the center of the mark portion. The encoder device according to claim 3, wherein the mark includes a figure provided in only one of two regions formed by dividing the mark portion by a straight line passing through the center of the mark portion. The encoder device according to claim 4, wherein the mark has a shape that is non-axisymmetric with respect to at least one straight line passing through the center of the disk. The encoder device according to claim 4, wherein the mark includes a figure provided in only one of two regions formed by dividing the mark by a straight line passing through the center of the disk. The encoder device according to any one of claims 1 to 11, wherein the imaging unit captures the entire area of the mark. The encoder device according to any one of claims 1 to 12, and the encoder device.
A drive device including a drive unit that supplies a drive force to the rotating shaft. With a mobile body
A stage device including the drive device according to claim 13, which moves the moving body. A driving device according to claim 1 3,
A robot device including an arm that is moved by the drive device. Imaging a mark containing a line whose direction changes due to the rotation of the rotation axis, and
An information acquisition method including obtaining rotation information of the rotation axis based on the number of intersections between the image of the line obtained by imaging and a predetermined line set in the captured image.

Images