JP3230789B2 - Optical position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical position detecting device for detecting a position of a table or the like of a machine tool when a linear motion is made and outputting position data, and in particular, an optical position detecting device for surely detecting the positional deviation. It relates to a detection device.

[0002]

FIG. 9 is a schematic view showing a conventional optical position detecting device and a processing machine using the conventional optical position detecting device. Note that a direction perpendicular to the paper surface is called an X axis, a vertical direction in the figure is called a Y axis, and a horizontal direction in the figure is called a Z axis. Generally, the optical position detecting device is composed of a main scale 110 on which graduations are recorded.
And a slider 120 having a function of reading a scale on the main scale 110 by being relatively displaced in the longitudinal direction with respect to the main scale 110 and detecting a position of the main scale 110 in the longitudinal direction. The main scale 110 of the optical position detecting device is usually mounted on a first member 1 called a bed of a processing machine.
The second member 2 moves relative to the first member in the Z direction, that is, in the longitudinal direction of the main scale.
Attached to. Further, a processing tool 3 is attached to the second member to perform desired processing. In the processing machine having such a configuration, the position of the second member with respect to the first member in the Z direction is detected by the optical position detecting device, the detected position data is read by the control device, and the second position is read using the actuator such as a motor. By moving the member in the Z direction on the first member, the processing point M of the processing tool 3 is accurately positioned at a desired position.

Next, FIG. 10 shows the internal configuration of a conventional optical position detecting device, and its function will be briefly described below. The above-described slider 120 includes a detection unit including the light emitting element 31, the collimator lens 32, the index scale 133, and the photoelectric conversion element 134, and reads a scale recorded on the main scale 110. The operation will be described in detail. After the light emitted from the light emitting element 31 and converted into a parallel light beam by the collimator lens 32 passes through the main scale 110 and the index scale 133,
The light enters the photoelectric conversion element 134 and is photoelectrically converted. As shown in FIG. 11, an optical grating is provided on the grating track of the main scale 110 such that the grating line direction is perpendicular to the longitudinal direction of the main scale. The index scale 133 is also provided with a lattice track corresponding to the lattice track of the main scale 110. Here, with respect to the main scale 110, the slider is the main scale 1
10 are relatively displaced in the longitudinal direction of the photoelectric conversion element 13
4 periodically changes the amount of light incident thereon, and a displacement signal can be obtained. Normally, this periodic displacement signal is counted, or the position is detected by further finely dividing it by interpolation.

[0004]

In the processing machine shown in FIG. 9, if the guide mechanism for guiding the movement of the second member is ideal, the second member can be moved on the first member without changing its posture. It moves linearly only in the Z direction. However,
Actually, the second member may be slightly displaced in the Y-direction or so-called pitching in which the second member rotates around the X-direction may occur due to a straightness error or play of the guide mechanism. When such a shift occurs, the detection point Da of the slider of the optical position detection device shown in FIG. 9 is set at the correct position on the main scale, but the processing point of the processing tool, That is, the cutting edge position M is shifted in the Z direction or the Y direction, and accurate machining cannot be performed.
For example, if the second member rotates to the left around the X axis due to pitching, the cutting edge is shifted by E and a machining error occurs. When the second member is displaced in the Y direction, the processing point M is naturally shifted in the Y direction, and a processing error occurs. The present invention has been made in order to solve the above-described problem, and has as its object not only the main scale longitudinal position, but also the amount of displacement perpendicular to the longitudinal direction and the rotation about the axis perpendicular to the main scale surface. An object of the present invention is to provide an optical position detecting device capable of detecting a displacement.

[0005]

In order to achieve the above object, an optical position detecting device according to the present invention comprises: a longitudinal position detecting grid track having grid lines perpendicular to the scale longitudinal direction; Swing detection grid tracks having grid lines parallel to the direction are respectively applied along the longitudinal direction of the scale, and the main scale attached to the first member and the main scale relative to the first member. Attached to the second member that moves only in the longitudinal direction, the light source and the index scale for position detection provided with a lattice track corresponding to the lattice track for longitudinal position detection on the main scale have transmitted or reflected the main scale. A photoelectric conversion element for photoelectrically converting light, and a grid line of the grid track for longitudinal position detection corresponding to the movement of the second member; A longitudinal position detecting means for detecting a position in the longitudinal direction of the main scale based on a change in a facing relationship between the index scale for detecting the position and the lattice track, and a light source and a swing on the main scale attached to the second member; A swing detection index scale provided with a lattice track corresponding to the movement detection lattice track, and a photoelectric conversion element for photoelectrically converting light transmitted or reflected by the main scale, and corresponding to the movement of the second member. Two swing detections for detecting a shift amount in a direction perpendicular to a longitudinal direction of the main scale by changing a facing relationship between a grid line of the swing detection grid track and a grid track of the swing detection index scale. Means and the two swing detection means are attached to the second member.
Deviation detected by each of the swing detection means.
Amount and longitudinal direction of the main scale between each swing detecting means
With respect to the first member based on a distance in a direction parallel to
A rotation centered on a direction perpendicular to the main scale surface of the second member
And a rotational deviation calculating means for determining the amount of roll deviation . Further, at least one slider provided with at least one of the longitudinal position detecting means and the swing detecting means is provided for one main scale.

[0006]

According to the optical position detecting apparatus of the present invention, a longitudinal position detecting lattice track having lattice lines perpendicular to the main scale longitudinal direction and a lattice line parallel to the longitudinal direction are provided on the main scale. A swing detection lattice track, and a longitudinal position is detected by longitudinal position detection means opposed to the position detection lattice track, and a shift amount in a direction perpendicular to the longitudinal direction is determined by the oscillation detection lattice track. It is detected by the swing detecting means facing the track. The rotational displacement calculating means also detects the rotational displacement generated around an axis perpendicular to the main scale surface by causing a plurality of swing detecting means to face the swing detecting lattice track .

[0007]

FIG. 1 shows a first embodiment of the present invention. FIG. 9 shows the relationship between the first member, the second member, and the processing tool.
Therefore, the description is omitted. According to this embodiment, one main scale 10 is attached to the first member, and three sliders 20 are attached to the second member.
21 and 22 are attached. Three sliders 20
The sliders 21 and 22 at both ends of the sliders 22 to 22 are provided with a rocking detecting section as a rocking detecting means for detecting a shift in the Y-axis direction perpendicular to the longitudinal direction of the main scale. Further, the center slider 20 is provided with a longitudinal position detecting section as longitudinal position detecting means for detecting a position in the longitudinal direction of the main scale.

Next, the main scale 10, the swing detecting section, and the longitudinal position detecting section used in this embodiment will be specifically described. FIG. 2 shows a main scale 10 used in the present embodiment. On the main scale 10, a swing detection grating track 11 and a longitudinal position detection grating track 12 are formed. The swing detection track 11 is an optical grating formed by, for example, etching or the like, and the grating line direction is the longitudinal direction of the main scale. The longitudinal position detection grating track 12 is also an optical grating formed in the same manner as the swing detection track 11, but the grating line direction is a direction perpendicular to the main scale longitudinal direction. The swing detecting section is shown in FIG. 3 and the operation will be described. The swing detection unit includes a light emitting element 31, a collimator lens 32, an index scale 33, and a photoelectric conversion element 34. Light emitted from the light emitting element 31 is converted into a parallel light beam by the collimator lens 32 to detect the swing of the main scale 10. The light passes through the grid track 11 and also passes through the grid track on the index scale 33, and
Is photoelectrically converted. The grid line direction of the grid track on the index scale 33 is formed so as to correspond to and be parallel to the swing detection grid track 11 on the main scale 10. When the swing detection unit having such a configuration is displaced in the Y direction with respect to the main scale 10 in response to the movement of each of the sliders 21 and 22, the grid lines on the main scale 10 and the grid lines on the index scale 33 And the amount of light incident on the photoelectric conversion element 34 also changes. From this change in light amount, the amount of displacement of the swing detection unit with respect to the main scale 10 in the Y direction can be detected. The operation in the longitudinal direction position detector is shown in FIG. The longitudinal position detecting unit includes a light emitting element 31, a collimator lens 32, an index scale 43, and a photoelectric conversion element 44. Light emitted from the light emitting element 31 is converted into a parallel light beam by the collimator lens 32, and the length of the main scale 10 is reduced. The light passes through the grid track 12 for detecting the directional position and also passes through the grid track on the index scale 43, and is photoelectrically converted by the photoelectric conversion element 44.
The grid line direction of the grid track on the index scale 43 is formed so as to correspond to and be parallel to the grid track 12 for longitudinal position detection on the main scale 10. When the longitudinal position detector having such a configuration is displaced in the Z direction with respect to the main scale 10 in response to the movement of the slider 20, the main scale 10
The facing relationship between the upper grid line and the grid line on the index scale 43 changes, and the amount of light incident on the photoelectric conversion element 44 also changes. The position in the Z direction of the longitudinal position detector with respect to the main scale 10 can be detected from the change in the amount of light.

Next, the operation of the optical position detecting device provided with the main scale 10, the swing detecting section and the longitudinal position detecting section will be described with reference to FIG. As described in the description of the related art, in the illustrated processing machine, if the guide mechanism for guiding the movement of the second member 2 is ideal, the second member 2 can be placed on the first member 1 without changing its posture. Moves linearly only in the Z direction. However, in reality, the second member 2 may be slightly displaced in the Y direction or so-called pitching in which the second member 2 rotates about the X direction may occur due to a straightness error or play of the guide mechanism. When such a displacement occurs, the detection point Da of the slider 20 of the optical position detection device is positioned at an accurate position on the main scale 10, but the processing tool 3
Is shifted in the Z direction or the Y direction, and accurate machining cannot be performed. For example, if the second member 2 rotates to the left around the X axis due to pitching, the cutting edge is shifted by E and a machining error occurs. When the second member 2 is displaced parallel to the Y direction, the processing point M is also
It shifts in the direction and causes a processing error. However, according to the present embodiment, if the second member 2 is displaced in the Y direction without changing the posture, the sliders 21 and 22 provided with the swing detection unit are provided in the same direction and the same amount in the Y direction. The shift amount is detected. In that case, the shift amount is corrected by moving the detected amount by a control device and an actuator (not shown) for controlling the position in the Y direction, and the machining point M of the machining tool 3 is set to an accurate position. Can be positioned. Further, when the second member 2 is rotated leftward about the point Da, for example, about the X direction as an axis, the sliders 21 and 22 provided with the swing detectors are provided in the opposite directions in the same amount in the Y direction. However, in this embodiment, the first deviation is obtained from the deviation amount obtained from the swing detection unit.
By providing the rotational deviation calculating unit 15 as a rotational deviation calculating means for calculating the rotational deviation about the direction perpendicular to the surface of the main scale 10 of the second member 2 with respect to the member 1, the rotational deviation can be obtained. Can be. For example, assuming that the shift amount is d, the gradient of the inclination is 2d / (L1 + L2). If the distance from the rotation center Da to the processing point M is L0, the shift amount E of the processing point M is 2d · L0 / (L1 + L).
It is represented by 2). Here, from the rotation center Da to the machining point M
If the angle between the line connecting the coordinate axes and the coordinate axis is known, the rotational displacement E which is the Y-direction component and the Z-direction component of the displacement E
y and Ez can be calculated respectively. Therefore, the Y-direction component E of the displacement of the processing point M is controlled by a control device and an actuator (not shown) for controlling the position in the Y direction.
By moving the machining point by y, the shift amount in the Y direction is corrected, and a controller and an actuator (not shown) for similarly controlling the position in the Z direction shift the Z of the shift of the machining point.
By moving the machining point by the direction component Ez, the Z direction shift amount is corrected, and the machining point M of the machining tool 3 can be positioned at an accurate position. Even when the displacement parallel to the Y-axis of the second member 2 and the rotational displacement occur simultaneously, the position of the processing point M can be easily and accurately positioned by combining the above methods. In the above description, the shift amount E of the processing point M is obtained by using the two sliders 21 and 22. However, it is possible to obtain the amount of rotational deviation although the accuracy is somewhat inferior.

A second embodiment of the present invention will be described with reference to FIG. The basic configuration is the same as that of the first embodiment, and a description thereof will be omitted. In this embodiment, two sliders 50 and 51 are attached to the second member 2. Of the two sliders, the slider 51 is provided with the above-described swing detection unit, and the other slider 50 is provided with both the swing detection unit and the above-mentioned longitudinal position detection unit. In this case, the position of the second member 2 in the Z direction can be detected by the longitudinal position detection unit in the slider 50. Also, the second
The displacement of the member 2 in the Y direction and the pitching about the X axis are detected by a swing detecting section in the slider 40 and a swing detecting section in the slider 51, and are corrected in the same manner as in the first embodiment. This makes it possible to easily and accurately position the processing point.

A third embodiment of the present invention will be described with reference to FIG. The basic configuration is the same as that of the first embodiment, and a description thereof will be omitted. In this embodiment, one slider 60 is attached to the second member 2. The slider 60 is provided with both the above-mentioned swing detection unit and one above-mentioned longitudinal position detection unit. In this case, the position of the second member 2 in the Z direction can be detected by the longitudinal position detection unit. In addition, the displacement of the second member in the Y direction and the pitching about the X axis are detected by two swing detection units,
By performing correction in the same manner as in the first embodiment, the position of the processing point can be easily and accurately positioned. FIG. 7 shows an example of the internal configuration of the slider in which the configuration in which the two swing detection units and the longitudinal position detection unit are combined is simplified. In this configuration, two grid tracks for swing detection and a grid track for longitudinal position detection are provided on one index scale 53 together. A set of light emitting elements 31 and a collimator lens 32 illuminate a range necessary for swing detection and longitudinal position detection. Light transmitted through the three lattice tracks on the main scale 10 and the index scale 53 is photoelectrically converted by the photoelectric conversion elements. According to this embodiment, the effect can be obtained with one slider, which contributes to space saving. Further, the slider itself can be further compacted by the integrated index scale 53 as shown in FIG. 7 and the configuration of one set of the light emitting element 31 and the collimator lens 32.

FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, when the main scale 10 described in the above embodiment is used as the first main scale,
A second main scale 120 is newly provided so as to be perpendicular to the main scale and parallel to the longitudinal direction. This second main scale 120 is provided with a second swing detection track 13 having lattice lines parallel to the longitudinal direction. Although not shown, the slider-side detecting means is provided with a second swing detecting section corresponding to the second swing detecting track 13. According to the embodiment configured as described above, not only the displacement of the second member in the Y direction but also the displacement in the X direction can be detected. In addition, by providing a plurality of swing detection units for the second swing detection track, it is possible to detect a displacement of the second member rotating around the Y axis, that is, a yawing component.
Therefore, according to this embodiment, in addition to the position of the second member in the Z direction, a shift in the Y direction, a shift in the X direction, and
It is possible to simultaneously detect a rotational deviation (pitching) about the axis and a rotational deviation (yaw) about the Y axis. In addition, in the detection means in each of the above embodiments,
Although the configuration is such that light transmitted through the main scale is photoelectrically converted, the same effect can be obtained by a configuration in which light reflected on the main scale is photoelectrically converted. Further, the present invention is characterized by having at least one or more sliders provided with one or more of one of longitudinal position detecting means and swing detecting means for one main scale. The combination of the longitudinal position detecting unit, the swing detecting unit, and the slider including these components is not limited to the above embodiments.

[0013]

According to the present invention, there is provided an optical position detecting device comprising one main scale mounted on a first member and provided with both a longitudinal position detecting lattice track and a swing detecting track, and a second member. The first position detection means and at least one or more swing detection means mounted on the
In addition to reading the position of the second member moving in the longitudinal direction of the main scale on the member, the amount of displacement of the second member in the direction perpendicular to the longitudinal direction of the main scale, The amount of rotation deviation about the direction perpendicular to the axis can be detected . Therefore, the position of the processing point of the processing tool on the second member can be accurately positioned by correcting and controlling the deviation amount detected by the control device or the actuator.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of a first embodiment of an optical position detecting device according to the present invention.

FIG. 2 is a schematic diagram showing a main scale used in the first embodiment.

FIG. 3 is a schematic diagram illustrating a swing detection unit according to the first embodiment.

FIG. 4 is a schematic diagram illustrating a longitudinal position detection unit according to the first embodiment.

FIG. 5 is a schematic diagram showing a configuration of a second embodiment.

FIG. 6 is a schematic diagram showing a configuration of a third embodiment.

FIG. 7 is a schematic diagram illustrating a swing detection unit and a longitudinal position detection unit according to a third embodiment.

FIG. 8 is a schematic diagram showing a main scale used in a fourth embodiment.

FIG. 9 is a schematic diagram showing a conventional optical position detecting device and a processing machine using the conventional optical position detecting device.

FIG. 10 is a diagram showing a configuration of a detecting means provided inside a conventional slider.

FIG. 11 is a schematic view showing a main scale used in a conventional optical position detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st member 2 2nd member 3 Processing tool 10,110,120 Main scale 111 Lattice track 11,13 Lattice detection lattice track 12 Longitudinal position detection lattice track 15 Rotational deviation calculation part 20,21,22,50 , 51, 60, 120 Slider 31 Light emitting element 32 Collimator lens 33, 43, 53, 133 Index scale 34, 44, 134 Photoelectric conversion element

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01D 5/00-5/62 G01B 11/00-11/30

Claims (2)

(57) [Claims] 1. A longitudinal position detecting grid track having grid lines perpendicular to the scale longitudinal direction and a swing detecting grid track having grid lines parallel to the scale longitudinal direction are respectively provided along the scale longitudinal direction. A main scale attached to a first member, and a second member attached to a second member that moves only in the longitudinal direction of the main scale relative to the first member, and detects a light source and a longitudinal position on the main scale. A position detection index scale provided with a grid track corresponding to the grid track, and a photoelectric conversion element for photoelectrically converting light transmitted or reflected by the main scale, wherein the longitudinal direction corresponding to the movement of the second member is provided. By the change of the facing relationship between the grid line of the position detection grid track and the grid track of the position detection index scale, A longitudinal position detecting means for detecting a position in the longitudinal direction of the main scale; and a swing detection attached to the second member and provided with a light source and a grating track corresponding to the swing detecting grating track on the main scale. And a photoelectric conversion element for photoelectrically converting light transmitted or reflected by the main scale, and a grid line of the swing detection grid track corresponding to the movement of the second member and the swing detection index. Two swing detecting means for detecting a shift amount in a direction perpendicular to the longitudinal direction of the main scale based on a change in the facing relationship with the lattice track of the scale; and two swing detecting means attached to the second member. Is
The amount of displacement detected by each of the swing detection means and the
The direction parallel to the longitudinal direction of the main scale between each swing detection means
Direction of the second member with respect to the first member based on the
The amount of rotational deviation about the axis perpendicular to the main scale surface
An optical position detecting device , comprising: a rotation deviation calculating means to be obtained. 2. The apparatus according to claim 1, further comprising at least one slider provided with at least one of said longitudinal position detecting means and said swing detecting means for one main scale. The optical position detecting device according to claim 1.