JP4469944B2 - Swing motion optical lever drive device - Google Patents

Description

  The present invention relates to a swing motion optical lever driving device in a beam tracking type laser interference length measuring device that measures the coordinates of a retroreflector while tracking a retroreflector moving in a three-dimensional space.

FIG. 4 shows a cross-sectional view of a conventional beam tracking type laser interference length measuring device using a swinging optical lever (see Patent Document 1). This apparatus is provided with a swinging movement light lever 201 in the optical path, and a laser beam is incident on the upper surface of a hemisphere 202 as a reflection surface so that the reflection beam can be changed in an arbitrary direction.
FIG. 5 shows an enlarged view of the swing motion light lever 201. As shown in FIG. The swinging motion optical lever 201 is designed to keep the eccentricity of the upper surface center 220 of the hemisphere 202 to about 0.1 to 0.25 μm and to keep the required eccentricity of the measurement origin at 1 μm or less. The spherical portion 202 is seated on a three-sphere spherical seat, and the spherical contactor 204 is in contact with the V-shaped surface of the V plate 205 fixed to the upper surface of the X moving table 210. That is, the two right and left tension springs 207 inclined from the vertical direction are attached to the connecting shaft 203 and the V plate 205 via the pins 206 and 208, respectively. The three steel balls 241 and the spherical contact 204 are in pressure contact with the V-shaped surface at the same time.
As the swing motion optical lever driving device, a moving table for operating the hemisphere 202 is driven by a motor and a feed screw.
In FIG. 4, the X-axis moving table 110 can be moved in the X direction by a motor 115 via a coupling 116 and a feed screw 114. Although not shown, the Y moving table 111 can be moved in the Y direction via a coupling and a feed screw by a motor in the same manner as the X axis. This Y moving system is assembled on the base plate 112 via a guideway 119.
Japanese Patent No. 3427182 (Claim 2, FIG. 1, FIG. 3)

In the swing motion optical lever driving device in the conventional beam tracking laser interference length measuring device, the spherical contact 204 at the lower end moves upward as the hemispherical mirror 202 rotates. Therefore, the rotation angle of the hemispherical mirror is limited within a range where the contact between the spherical contactor 204 and the V plate 205 is maintained, and there is a problem that the beam scanning range of the beam tracking type laser interferometer is narrowed. . Further, since a motor and a feed screw are used for driving, and each of them is arranged in a right angle direction, there is a problem that the apparatus becomes large.
The present invention has been made in view of such problems, and an object of the present invention is to provide a small-sized swing motion optical lever driving device having a wide beam scanning range in a beam tracking type laser interference length measuring apparatus.

In order to solve the above object, the present invention is configured as follows.
According to a first aspect of the present invention, there is provided a swing motion optical lever driving device for a beam tracking laser interferometer, in which the spherical portion of a hemispherical mirror is seated on a three-sphere spherical seat. For driving, two outer and inner arc-shaped motors are arranged so that the movers are orthogonal to each other so that the intersection of the rotation axes of the movers matches the reflection center point of the hemispherical mirror. The three-sphere spherical seat frame that holds the hemispherical mirror has a shape that does not interfere with the beam scanning range scanned by the hemispherical mirror, the shaft is fixed to the lower part of the hemispherical mirror, and the lower end of the shaft contacts The child has a substantially disk shape, and is provided with a flat portion having a flat surface at three locations around the child. The contact is housed in a recess provided in the movable element of the inner arc-shaped motor, and the 3 The plane of the place By placing the small spheres in two places and the springs in the other one place, the flat portion is pressed by the spring force against the concave wall surface of the mover of the inner arc-shaped motor, and the outer and inner sides are pressed. And a power transmission device having a built-in spring for seating the spherical surface of the hemispherical mirror on the three-spherical spherical seat. .
In the invention according to claim 2, the first plane among the three planes is composed of two planes that are bent at 90 ° to each other, and the power transmission steel balls are in contact at two points, The two planes are in contact with the power transmission steel ball at one point, and the third plane is in contact with and pressed against the power transmission spring.
According to a third aspect of the present invention, the arc-shaped motor has a detent stop position where the motor movable element is held by a detent torque larger than the own weight holding torque of the motor movable element within the operating range. Features.
According to a fourth aspect of the present invention, the arc-shaped motor is configured as a system that shuts off the power after operating to the detent stop position when the power is cut off, and from the detent stop position to the arc-shaped motor when the power is turned on. It operates in the direction of the Z-phase signal, which is the origin signal of the attached position detector, detects the Z-phase signal, and performs origin return.

According to the first and second aspects of the present invention, in the swing motion optical lever drive device of the beam tracking type laser interference length measuring device, the swing motion configured by setting the spherical portion of the hemispherical mirror on the three-sphere spherical seat. In order to drive the optical lever, two outer and inner arc-shaped motors are arranged so that the movers are orthogonal to each other, and the intersection thereof coincides with the reflection center point of the hemispherical mirror. The three-sphere spherical seat frame that holds the hemispherical mirror has a shape that does not interfere with the beam scanning range scanned by the hemispherical mirror, so the beam scanning range of the beam tracking laser interferometer is expanded and the measurement range is increased Can be expanded compared to
In addition, since the swing motion optical lever driving device can be configured in a small size, even when four sets of beam tracking type laser interference length measuring devices are used to track and measure the position of the retroreflector to be measured a predetermined number of times, space saving is achieved. Can be installed, and the installation workability of the beam tracking laser interferometer can be improved.
Further, since the tilt angle of the hemispherical mirror and the rotation angle of each motor of the swing motion optical lever drive device coincide with each other, the feed amount and hemisphere of the X and Y table as in the drive device configured with an X, Y table and a feed screw. There is no need to convert the tilt angle of the mirror, the control is simple, and the tracking performance can be improved.
Further, the two small spheres fixed to the inner motor movable element of the arc-shaped motor and the flat portion provided on the contact at the tip of the shaft fixed to the hemispherical mirror are pressed by a spring, so that the two-axis operation of the motor is performed. Since the power transmission device incorporating the spring for transmitting to the hemispherical mirror and for allowing the spherical surface of the hemispherical mirror to be seated on the three-spherical spherical seat is provided, the biaxial motion by two arc motors is hemispherical. It can be transmitted to the mirror without backlash, the rotation axis of each arc-shaped motor and the inclination angle of the hemispherical mirror match, and the hemispherical mirror can be operated by the amount of movement of each arc-shaped motor.
Also, by setting the hemispherical mirror holding spring to the optimal spring force that can be held by the hemispherical mirror, the motor driving torque is reduced, the motor part is miniaturized, and the swing motion optical lever drive device is made compact. it can.
According to a third aspect of the present invention, the arc-shaped motor is configured to have a detent stop position where the motor movable element is held by a detent torque larger than the own weight holding torque of the motor movable element within the operating range. When the power is turned off, the motor mover does not hit the mechanical stopper at the detent stop position provided in the operating range, and the accuracy of the swinging light lever drive device due to the impact does not occur. But it can be installed.
According to a fourth aspect of the present invention, the arc-shaped motor is configured as a system that shuts off the power after operating to the detent stop position when the power is cut off, and the arc-shaped motor is moved from the detent stop position when the power is turned on. The position detector attached to the sensor moves in the direction of the Z-phase signal, detects the Z-phase signal, and performs home return, so there is no need to check the position of the motor armature when the power is turned on. When four sets of long devices are used to track and measure the position of a retroreflector that is a measurement target a predetermined number of times, the measurement target is large and the beam tracking laser interference length measurement device is installed at a distance. Even when necessary, measurement can be performed efficiently.
Further, even when it is necessary to install a device in a temperature-controlled space in order to perform precise measurement, the measurement can be performed without entering the temperature-controlled space.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1A and 1B are diagrams showing a swing motion optical lever driving device according to an embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a longitudinal sectional view.
2A and 2B are diagrams showing a power transmission device of a hemispherical mirror and a motor movable element in the swing motion optical lever driving device shown in FIG. 1, wherein FIG. 2B is a longitudinal sectional view, and FIG. FIG.
FIG. 3 is a diagram showing the detent torque characteristics of the arc motor of the swing motion optical lever driving device.

In FIG. 1, 1 is a swing motion light lever drive device, 2 is a swing motion light lever, and 3 is a hemispherical mirror having a reflective surface for irradiating a retroreflector with laser light on its upper surface. Reference numeral 4 denotes a shaft to which the power of the mover of the swing motion optical lever driving device 1 is transmitted. Reference numeral 5 denotes a spherical steel ball on which the hemispherical mirror 4 is seated. Reference numeral 6 denotes a reflection center point of the hemispherical mirror 4. Reference numeral 7 denotes an inner shaft movable element of the arc-shaped motor arranged on the inner side. Reference numeral 8 denotes an inner shaft stator that drives the inner shaft mover 7, and the inner shaft mover 7 and the inner shaft stator 8 constitute an arc motor. An inner shaft position detector 9 detects the position of the inner shaft. Reference numeral 10 denotes an outer shaft movable element of an arc motor arranged on the outer side of the inner shaft motor so that the rotation axis is orthogonal to the rotation axis of the inner shaft and the intersection thereof is located at the reflection center point of the hemispherical mirror. The outer shaft stator 10 drives the shaft mover 10, and the outer shaft mover 10 and the outer shaft stator 11 constitute an arc motor. An outer shaft position detector 12 detects the position of the outer shaft. Reference numeral 13 denotes a three-sphere spherical seat frame for holding a hemispherical mirror in the swinging movement optical lever 2.
In FIG. 2, reference numeral 14 denotes a contact having a flat portion provided at the tip of the shaft 4 fixed to the hemispherical mirror 3. Reference numeral 15 denotes two power transmission steel balls (15a, 15b) fixed in a recess 7a provided in the inner shaft movable element 7. Reference numeral 16 denotes a power transmission spring for pressing the two power transmission steel balls 15 a and 15 b through the contact 14, and is provided on the inner shaft movable element 7. Reference numeral 17 denotes a hemispherical mirror holding spring for seating the hemispherical mirror 3 on a three-spherical spherical seat. Reference numeral 18 denotes a spring holder for holding a hemispherical mirror holding spring 17. The hemispherical mirror 3 is placed on a three-spherical spherical seat by pressing the contact 14 of the shaft 4 by the hemispherical mirror holding spring 17 held in the spring holder 18. I am letting.

Next, the operation will be described.
As shown in FIG. 2, the swing motion optical lever driving device 1 includes two power transmission steel balls 15 a and 15 b fixed to the inner shaft movable element 7 and a hemispherical mirror 3 of the small ball swing motion optical lever 2. The two-axis motion by the two arc motors is transmitted to the hemispherical mirror 3 by pressing the flat portion provided on the contact 14 at the tip of the shaft 4 fixed to the power transmission spring 16. The contact 14 has a substantially disk shape, and planes 14a, 14b, and 14c are formed at three places around the contact. Of these three planes, the plane 14a is composed of planes 14a1 and 14a2 bent at 90 ° to each other, and the power transmission steel balls 15a are in contact with each other at two points. The flat surface 14b is in contact with the power transmission steel ball 15b at one point, and the flat surface 14c is in contact with and pressed against the power transmission spring 16.

These two power transmission steel balls 15a and 15b are fixed so that their positions are 120 ° from the center of the disk-shaped contact 14 and contacted by a power transmission spring 16 disposed on the opposite side. The child 14 is pressed against the two power transmission steel balls 15a and 15b. By doing so, the operation of the inner shaft movable element 7 can be transmitted to the contact element 14 without rotating the contact element 14, the shaft 4 and the hemispherical mirror 3. The axial motion can be transmitted to the hemispherical mirror 3 without backlash.
Since the inner shaft mover 7 and the inner shaft stator 8 are arranged on the outer shaft mover 10 (FIG. 1B), the operation of the outer shaft mover 10 is performed via the inner shaft mover 7. It is transmitted to the contact 14. As a result, the rotational axes of the inner shaft movable element 7 and the outer shaft movable element 10 are orthogonal to each other, and the intersection is located on the reflection center point 6 of the hemispherical mirror 3, so that the swing motion light lever drive is performed. The rotation axis of each arc-shaped motor of the apparatus 1 and the inclination angle of the hemispherical mirror 3 coincide with each other, and the hemispherical mirror 3 can be operated by the operation amount of each arc-shaped motor.
In addition, a spring holder 18 is disposed on the outer side of the shaft 4 on the side of the contact 14, the spring holder 18 is fixed to the inner shaft movable element 21, and a hemispherical mirror holding spring 17 is disposed on the outer periphery of the shaft 4. By interposing the spring 17 between the contact 14 and the spring holder 18, the hemispherical mirror holding spring 17 is held, and the hemispherical mirror 3 is seated on the three-spherical spherical seat.
The frictional resistance caused by the contact between the hemispherical mirror 3 and the three-spherical spherical seat is included in the driving torque of the motor, but by setting the hemispherical mirror holding spring 17 to an optimum spring force that can be held by the hemispherical mirror 3, The drive torque of the motor can be reduced, and the motor unit can be reduced in size.
In addition, although the example which used the compression spring for the hemispherical mirror holding spring 17 in order to comprise a power transmission device small was shown, it can also comprise using a tension spring.
Further, the frame 13 of the hemispherical mirror holding three-sphere spherical seat is formed in a shape that does not disturb the light beam scanning range scanned by the hemispherical mirror 3.
As described above, since the two-axis motion of the two motors is transmitted to the hemispherical mirror 3 by the structure described above, the beam scanning range of the beam tracking laser interference length measuring device is expanded and the measurement range is expanded compared to the conventional one. it can.
In addition, since the swing motion optical lever driving device 1 can be configured in a small size, even when four sets of beam tracking type laser interference length measuring devices are used to track and measure the position of a retroreflector that is a measurement target a predetermined number of times, it can be saved. Space can be installed, and the installation workability of the beam tracking laser interferometer can be improved.
Further, since the tilt angle of the hemispherical mirror 3 and the rotation angle of each motor of the swing motion light lever drive device 1 coincide, the feed amount of the X and Y table as in the drive device constituted by the X, Y table and the feed screw. Therefore, it is not necessary to convert the tilt angle of the hemispherical mirror, and control is simple and the tracking performance can be improved.

Next, a method for holding the motor mover and returning to the origin when the power is shut off will be described.
Regarding the motor mover holding when the power is shut off, since this motor is an arc motor, the detent torque due to the terminal effect at both ends of the motor movers 7 and 10 (the mover can be pulled into a specific rotational position even in the non-excited state). On the other hand, depending on the installation posture of the swing motion optical lever driving device 1, torque for holding the motor movable elements 7 and 10 is required. The detent torque can be set according to the shape of the motor.
In view of this, the motor operating ranges of the motors are configured to have detent stop positions where the motor movable elements 7 and 10 are held by a detent torque larger than the own weight holding torque of the motor movable elements when the power is shut off.
In FIG. 3, the horizontal axis indicates the position of the motor movable element, and the vertical axis indicates the detent torque. In this example, there are two positions where the detent torque becomes + to-in the operating range: ± 20 °, and the two positions are detent stop positions.
With the above configuration, when the power is shut off, the motor mover does not hit the mechanical stopper by stopping at the detent stop position provided in the operation range, and the accuracy of the swing motion optical lever driving device 1 due to the impact does not occur. The device can be installed in any orientation.
As a method of returning to the origin, there is a method of providing a separate origin sensor, and there is a method of providing a separate brake for holding the motor mover when the power is shut off. However, in order to configure the swing motion optical lever drive device 1 in a small size, it is configured by the following method that does not use an origin sensor or a brake. The system is configured to shut off the power after operating to the detent stop position when the power is cut off. When the power is turned on, the Z phase signals of the position detectors 9 and 12 attached to the two arc-shaped motors from the detent stop position are configured. To return to the origin by detecting the Z-phase signal.
In the example of FIG. 3, since there are two detent stop positions, one of the two detent stop positions may be selected. According to this return-to-origin method, there is no need to check the position of the motor mover when the power is turned on, so four sets of beam tracking laser interference length measuring devices are used, and the position of the retroreflector to be measured is determined a predetermined number of times. In the case of tracking measurement, even when the measurement target is large and it is necessary to install the beam tracking type laser interference length measuring apparatus at a distance, the measurement can be performed efficiently. Further, even when it is necessary to install a device in a temperature-controlled space in order to perform precise measurement, the measurement can be performed without entering the temperature-controlled space.

According to the present invention, the beam scanning range of the beam tracking type laser interference length measuring device can be expanded, the measurement range can be expanded as compared with the conventional one, and the swing motion light lever driving device can be configured in a small size. Space-saving installation is possible even when the set of four laser interferometers is used to track and measure the position of the retroreflector to be measured a predetermined number of times. Installation workability of the beam tracking laser interferometer Can also be improved.
Further, since the tilt angle of the hemispherical mirror and the rotation angle of each motor of the swing motion light lever drive device coincide, the feed amount and hemisphere of the X and Y table as in the drive device constituted by the X, Y table and feed screw. There is no need to convert the tilt angle of the mirror, the control is simple, and the tracking performance can be improved.
Furthermore, when the power is turned off, the motor mover does not hit the mechanical stopper at the detent stop position provided within the operating range, so the device can be installed in any direction. Return to origin without confirmation.
Due to the above features, the beam tracking laser interferometer is required for installation of large objects that need to be installed at a distance, and for precision measurement that requires installation of the device in a temperature-controlled space. Is also applicable.
Further, the present invention can be applied to a purpose of detecting a positioning error of a robot by attaching a retro-reflector to the working shaft end of an industrial robot and tracking with a laser interferometer.

It is a figure which shows the swing motion optical lever drive device based on embodiment of this invention, (a) is a top view, (b) is a longitudinal cross-sectional view. It is a figure which shows the power transmission device of the hemispherical mirror and motor mover in the swing motion optical lever drive device shown in FIG. It is. It is a figure which shows the detent torque characteristic of the circular arc motor of the swing motion optical lever drive device which concerns on embodiment of this invention. It is sectional drawing of the conventional beam tracking type | formula laser interference length measuring apparatus. It is sectional drawing of a swing motion light lever used for the conventional beam tracking type laser interference length measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Swing motion optical lever drive device 2 Swing motion light lever 3 Hemispherical mirror 4 Shaft 5 Steel ball 6 Reflection center point 7 Inner axis | shaft movable element 7a Recessed part provided in inner axis movable element 8 Inner axis stator 9 Detecting inner axis position Device 10 Outer shaft movable element 11 Outer shaft stator 12 Outer shaft position detector 13 Three-spherical spherical seat frame 14 for holding a hemispherical mirror Contact 14a1, 14a2, 14b, 14c Flat surface 15 (15a, 15b) formed on the contact Power transmission steel ball 16 Power transmission spring 17 Hemispherical mirror holding spring 18 Spring holder

Claims (4)

In the swing motion optical lever driving device of the beam tracking type laser interferometer, two outer sides are used to drive the swing motion optical lever configured by setting the spherical surface of the hemispherical mirror on the three-sphere spherical seat. And an arcuate motor on the inner side so that the movers are orthogonal to each other, and the intersection of the rotation axes of the movers is aligned with the reflection center point of the hemispherical mirror. The holding three-sphere spherical seat frame is shaped so as not to obstruct the beam scanning range scanned by the hemispherical mirror, the shaft is fixed to the lower part of the hemispherical mirror, and the contact at the lower end of the shaft has a substantially disc shape. and it has a flat portion forming a plane at three locations surrounding provided, accommodating the contacts in a recess provided in the movable element of the inner arcuate motor and the two positions of the plane of the three positions Small balls each By placing the spring in the other one place, both the small spheres are pressed against the wall surface of the concave portion of the mover of the inner arc-shaped motor by spring force of the flat portion, and 2 of the outer and inner arc-shaped motors. A swinging motion optical lever drive device comprising a power transmission device having a built-in spring for transmitting axial motion to the hemispherical mirror and for allowing the spherical surface of the hemispherical mirror to be seated on a three-spherical spherical seat .   Of the three planes, the first plane is composed of two planes bent at 90 ° to each other, and the power transmission steel balls are in contact at two points, and the second plane is in contact with the power transmission steel balls. 2. The swing motion optical lever driving device according to claim 1, wherein the swinging optical lever drive device is in contact at one point, and the third plane is in contact with and pressed against a power transmission spring.   The arc-shaped motor is configured to have a detent stop position in which the motor movable element is held by a detent torque larger than the own weight holding torque of the motor movable element within the operation range. Swing motion light lever drive device.   The arc-shaped motor is configured in a system that shuts off the power after operating to the detent stop position when the power is shut off, and when the power is turned on, the origin signal of the position detector attached to the arc motor from the detent stop position 2. The swing motion optical lever drive device according to claim 1, wherein the Z-phase signal is detected by operating in the direction of the Z-phase signal, and the origin return is performed.

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