JP3844423B2 - Distance measuring device and distance measuring method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a distance measuring device and a distance measuring method, and more particularly to a distance measuring device and a distance measuring method suitable for use in measuring a moving distance of a moving body that moves in a predetermined direction.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a moving body that linearly moves in a predetermined direction and a linear encoder that outputs an output value corresponding to the movement of the moving body are provided. Based on the output value of the linear encoder, the moving body There is known a distance measuring device that measures the moving distance of the.
[0003]
As a linear encoder disposed in such a distance measuring device, for example, an optical linear encoder can be used. The optical linear encoder has a main scale in which grid-like slits are formed at a predetermined pitch, a light source, and a light receiving element, and the light source and the light receiving element are connected to a moving body with the main scale sandwiched therebetween. By moving with the movement, an output value corresponding to the movement of the moving body is output.
[0004]
However, when the main scale of an optical linear encoder is made of resin, it is easily affected by temperature, humidity, etc., and the main scale expands and contracts in response to changes in temperature, humidity, etc. Will change. As a result, the pitch of the slit formed in the main scale changes, and the output value output from the optical linear encoder may not be an accurate output value according to the movement of the moving body. It was.
[0005]
For this reason, in a conventional distance measuring device, a temperature sensor for measuring temperature and a humidity sensor for measuring humidity are arranged to measure temperature and humidity in an environment where the distance measuring device is installed. A correction table in which correction values corresponding to various temperatures and humidity are stored in advance is prepared.
[0006]
In such a distance measuring device, a process for comparing the measurement result of the temperature and humidity with the sensor and the correction table is performed to obtain a correction value according to the environment in which the distance measuring device is disposed. By using the obtained correction value, even if the slit pitch changes due to the influence of temperature and humidity and an accurate output value is not output from the optical linear encoder, the moving distance of the moving body is accurate. To be able to measure.
[0007]
However, in such a conventional distance measuring device, a temperature sensor, a humidity sensor, and the like must be provided, so that there is a problem that the manufacturing cost increases and the cost becomes high.
[0008]
In addition, it is necessary to prepare a complex correction table based on a combination of two parameters of temperature and humidity in advance, and in the correction using the correction value based on such a complicated correction table, the accurate moving distance of the moving object is highly accurate. There was a problem that it could not be measured.
[0009]
Therefore, in order to solve the problems in the conventional distance measuring apparatus as described above, an optical linear encoder having a main scale formed of a material that is not easily affected by temperature, humidity, or the like, for example, glass. There has been proposed a distance measuring device arranged.
[0010]
In such a distance measuring device, the main scale is made of glass, so the main scale is unlikely to expand or contract due to the influence of temperature, humidity, etc. The output value to be output is an accurate output value according to the movement of the moving body.
[0011]
However, since an optical linear encoder having a main scale formed of glass is expensive, if an optical linear encoder having a main scale formed of glass is disposed in a distance measuring device, the manufacturing cost is reduced. The problem was that it would increase and become expensive.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of the various problems of the prior art as described above, and the object of the present invention is that even if it is affected by the temperature and humidity in the environment in which it is placed. An object of the present invention is to provide an inexpensive distance measuring device and a distance measuring method capable of measuring an accurate moving distance with high accuracy while minimizing the influence.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention comprises a motor that rotates by a predetermined angle in accordance with a predetermined signal and steps. A driving belt having a glass core wire for transmitting the driving force of the motor, and via the driving belt; It is moved by the driving force of the motor Work table When, Detection that includes a main scale portion made of a resin having a predetermined lattice-shaped slit, a light source, a lens, and a light receiving element, and is disposed so as to sandwich the main scale portion and moves together with the work table. And the above Work table Is moved by the motor Above detector Move above Work table Output the output value according to the moving distance of An optical linear encoder, Based on the number of steps engraved by the motor, Optical linear Above per unit output value output from encoder Work table Determining means for determining the moving distance of the above, and the above determined by the determining means Optical linear Above per unit output value output from encoder Work table And the above moving distance Optical linear Based on the output value output from the encoder Work table And a distance measuring means for measuring the moving distance.
[0014]
Moreover, the invention according to claim 2 of the present invention is a motor driving force that rotates by a predetermined angle in accordance with a predetermined signal and ticks the step. Is transmitted to the work table via a driving belt having a glass core wire, and the driving force of the motor By above Work table Is moved by a predetermined reference movement distance, and the above-mentioned predetermined reference movement distance is Work table The first step of storing the number of steps engraved by the motor when moving the motor in correspondence with the predetermined reference movement distance, and the number of steps stored in the first step by the motor. Via the drive belt the above Work table When you move Detection that includes a main scale portion made of a resin having a predetermined lattice-shaped slit, a light source, a lens, and a light receiving element, and is disposed so as to sandwich the main scale portion and moves together with the work table. And when the work table is moved by the motor, the detection unit moves and outputs an output value corresponding to the movement distance of the work table. A second step of storing the output value output from the encoder, and the above-mentioned stored in the second step Optical linear From the output value output from the encoder and the predetermined reference movement distance, Optical linear Above per unit output value output from encoder Work table Determining the moving distance of the Optical linear Above per unit output value output from encoder Work table And the above moving distance Optical linear Based on the output value output from the encoder Work table And a third step of measuring the moving distance.
[0015]
Therefore, according to the first and second aspects of the present invention, based on the number of steps carved by the motor, Optical linear Per unit output value output from the encoder Work table The travel distance of this is determined Optical linear Per unit output value output from the encoder Work table The travel distance of Optical linear Based on the output value output from the encoder Work table Therefore, even if it is affected by the temperature and humidity in the environment in which it is placed, the influence can be kept to a minimum, and the accurate movement distance can be measured with high accuracy.
[0016]
Also, it is not necessary to install a temperature sensor or humidity sensor. Together with , Optical linear encoder The main scale part is inexpensive Formed by resin The Therefore, an accurate movement distance can be measured with high accuracy at low cost.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a distance measuring device and a distance measuring method according to the present invention will be described in detail with reference to the accompanying drawings.
[0018]
FIG. 1 shows a schematic configuration explanatory diagram of an example of an embodiment of a coordinate measuring device provided with a distance measuring device according to the present invention, and FIG. 2 shows a part of the view from the arrow A in FIG. FIG. 3A is an enlarged schematic diagram illustrating the schematic configuration centered on the linear encoder 20. FIG. 3A is an enlarged view of a part of FIG. The schematic configuration explanatory view shown in FIG.
[0019]
The coordinate measuring apparatus 10 includes a fixed base member 12, a support 14L, 14R vertically erected on the base member 12 at both left and right ends of the base member 12, and a rear connecting the two left and right supports 14L, 14R. Two rails 18-1, 18 extending on the member 16 and the base member 12 in the Y-axis direction (refer to the reference diagram showing the coordinate system in FIG. 1) and arranged in parallel with each other. -2, linear encoder 20 extending in the Y-axis direction on the base member 12 and disposed in the vicinity of the rail 18-1, and slide parts (not shown) on the two rails 18-1 and 18-2. 1), and a work table 22 movably arranged in the Y-axis direction via the Z-axis, and a X-axis direction (reference diagram showing a coordinate system in FIG. 1) via a slide bearing (not shown) on the rear member 16. ) Movably disposed on the carriage 24, and disposed on the carriage 24 so as to face the work table 22, and in the Z-axis direction (coordinates in FIG. 1) orthogonal to the X-axis direction and the Y-axis direction. And a scanning device 26 that is movably arranged in the reference diagram showing the system).
[0020]
Here, in this coordinate measuring apparatus 10, the drive of the motor which is a drive means is controlled according to predetermined resolution by control of the microcomputer 100 mentioned later. By driving the motor, the scanning device 26 is moved in the Z-axis direction, the carriage 24 is moved in the X-axis direction along the rear member 16, and the work table 22 on which the object 200 to be measured is placed is moved. It is moved in the Y-axis direction along the rails 18-1 and 18-2.
[0021]
Therefore, the relative positional relationship between the scanning device 26 and the object to be measured 200 placed on the work table 22 is such that the scanning device 26 can move in the X-axis direction and the Z-axis direction. Since 200 can move in the Y-axis direction, the scanning device 26 can eventually move with respect to the DUT 200 in the three-dimensional directions of the X-axis direction, the Y-axis direction, and the Z-axis direction.
[0022]
The coordinate measuring apparatus 10 is controlled by the microcomputer 100 (see FIG. 4) for the entire operation including the motor drive control. The detailed description thereof will be described later. To do.
[0023]
A three-dimensional object to be measured 200 is fixedly placed on the substantially rectangular upper surface portion 22 a of the work table 22. The DUT 200 is an object having a three-dimensional spatial extent, and the object has a predetermined shape.
[0024]
On the lower surface portion 22b of the work table 22, a guide portion 22c is provided so as to extend linearly in the Y-axis direction. The guide portion 22c is slidably engaged on linearly extending rails 18-1 and 18-2, and movement of the work table 22 in the Y-axis direction is allowed.
[0025]
More specifically, the driving force of the motor 36 is transmitted to the work table 22 via the driving belt 30 disposed in the vicinity of the linear encoder 20. Moves linearly in the Y-axis direction (see FIG. 3A).
[0026]
Specifically, the left end portion 22 </ b> L of both end portions along the Y-axis direction of the work table 22 is fixed to the drive belt 30.
[0027]
The drive belt 30 has a glass core wire. Therefore, the extent to which the drive belt 30 expands and contracts according to changes in temperature, humidity, and the like is extremely small, and the drive belt 30 is hardly affected by temperature, humidity, and the like. The drive belt 30 is stretched endlessly between a pulley 32-1 and a pulley 32-2 disposed on the base member 12.
[0028]
The motor 36 can be constituted by, for example, a stepping motor, and a motor gear 38 is disposed on a rotation shaft (not shown) of the motor 36. The motor 36 is arranged so that the gear 34 arranged coaxially with the pulley 32-1 and the motor gear 38 mesh with each other.
[0029]
The motor 36 is rotated stepwise by a predetermined angle in a predetermined direction in accordance with the number of pulses of a control pulse signal output by the control of a microcomputer, which will be described later. That is, the number of steps engraved by the motor 36 matches the number of pulses of the control pulse signal.
[0030]
The rotation of the rotating shaft caused by the rotation of the motor 36 is transmitted to the pulley 32-1 via the motor gear 38 and the gear 34 to cause the pulley 32-1 to rotate, and the rotation of the pulley 32-1. As the drive belt 30 moves, the work table 22 disposed on the drive belt 30 moves in the front-rear direction in the Y-axis direction.
[0031]
In this embodiment, when the motor 36 rotates clockwise (in the direction of arrow a shown in FIG. 3A) in accordance with a predetermined control pulse signal, the pulley 32-1 rotates in the counterclockwise direction ( Rotating in the direction of arrow b shown in FIG. 3A, the work table 22 disposed on the drive belt 30 moves linearly from the front side to the rear side in the Y-axis direction.
[0032]
On the other hand, when the motor 36 rotates counterclockwise (in the direction of arrow c shown in FIG. 3A) in accordance with a predetermined control pulse signal, the pulley 32-1 rotates clockwise (FIG. 3A). The work table 22 disposed on the drive belt 30 moves linearly from the rear side to the front side in the Y-axis direction.
[0033]
Next, the linear encoder 20 is an optical (transmission type) linear encoder, and includes a main scale unit 20a having a predetermined lattice-shaped slit, a light source, a lens, and a light receiving element, and a main scale. It is comprised by the detection part 20b arrange | positioned so that the part 20a may be inserted | pinched (refer FIG. 2).
[0034]
The main scale portion 20a is made of resin.
[0035]
The main scale portion 20a of the linear encoder 20 is fixedly disposed on the left side of the base member 12 so that the extending direction coincides with the Y-axis direction. On the other hand, the detection portion 20b of the linear encoder 20 is fixedly disposed on the outer surface 22e of the attachment portion 22d protruding from the left end portion 22L along the Y-axis direction of the work table 22.
[0036]
Therefore, as the work table 22 moves in the Y-axis direction, the detection unit 20b of the linear encoder 20 fixedly disposed at the left end portion 22L of the work table 22 has a main scale unit 20a. Is moved in the Y-axis direction with the
[0037]
The linear encoder 20 outputs a pulse signal corresponding to the movement distance of the work table 22 in the Y-axis direction when the work table 22 moves linearly in the Y-axis direction. The pulse signal output as a digital signal from the linear encoder 20 is input to the microcomputer 100 described later.
[0038]
The scanning device 26 is configured by a contact sensor having a piezoelectric element (not shown). By repeating the upward movement (rise) and the downward movement (downward) in the Z-axis direction, The tip 27a of the contact 27 of the contact sensor is lowered in the Z-axis direction and brought into contact with the surface 200a of the object 200 to be measured (in this specification, “in the surface 200a of the object 200 to be measured) (The portion where the tip 27a of the contact 27 is lowered and contacted in the Z-axis direction is referred to as a “contact point” as appropriate).
[0039]
A change in voltage at the contact point of the contact 30 is output from the scanning device 26 and input to the microcomputer 100 described later.
[0040]
Next, FIG. 4 shows a block diagram of a control system for controlling the entire operation of the coordinate measuring apparatus 10 having the distance measuring apparatus according to the present invention. Control of the operation is performed.
[0041]
The micro computer 100 includes a central processing unit (CPU) 102 that executes processing in accordance with a program stored in a read-only memory (ROM) 104, which will be described later, a ROM 104 that stores a program that the CPU 102 executes, Working data when the coordinate measuring device 10 according to the present invention is operated under the control of the coordinate data storage unit 106-1 for storing the coordinate data obtained by the operation of the coordinate measuring device 10 according to the present invention under control or the control of the CPU 102. And a random access memory (RAM) 106 in which an area as an area is set.
[0042]
Here, the ROM 104 can be configured by, for example, an EEP-ROM of PROM (Programmable read only memory), and in the manufacturing process of the coordinate measuring apparatus 10, reference pulse number data to be described later is written.
[0043]
The micro computer 100 is connected to a motor 36, a scanning device 26, a linear encoder 20, and the like, and a signal indicating a change in voltage at the contact point of the contact 27 transmitted from the scanning device 26 or linear. A pulse signal output from the encoder 20 is input to the microcomputer 100.
[0044]
Further, a display device 108 constituted by a liquid crystal display device (LCD) or the like is connected to the micro computer 100, and an X coordinate, a Y coordinate, and a Z coordinate of a measurement point indicated by coordinate data described later are displayed in real time. Is done.
[0045]
In the coordinate measuring apparatus 10, a linear encoder (not shown) that outputs a pulse signal corresponding to the movement distance of the carriage 24 in the X-axis direction and the movement distance of the scanning device 26 in the Z-axis direction. A linear encoder (not shown) for outputting a pulse signal is provided. The pulse signals output from these linear encoders are also input to the microcomputer 100.
[0046]
In the above configuration, the operation of the coordinate measuring apparatus 10 described above will be described with reference to FIGS. 3B, 3C, and 3D and FIG.
[0047]
FIG. 5 is an explanatory diagram conceptually showing an operation flow of the coordinate measuring apparatus 10 including the distance measuring apparatus according to the present invention.
[0048]
First, the coordinate measuring apparatus 10 is subjected to a correction process at the time of shipment (step S502 and the process) after the assembly of various members is completed in the manufacturing process in the factory, and after the shipping process, until the user actually starts using it. Step S504) and use correction processing (steps S510 to S514) are performed.
[0049]
The shipping correction process is a correction process that is performed when the assembly of various members in the manufacturing process in the factory is finished and the process proceeds to the shipping process for the coordinate measuring apparatus 10.
[0050]
Specifically, first, the coordinate measuring apparatus 10 is placed in a predetermined environment, for example, in an environment of a temperature of 20 ° C. and a humidity of 50%, and adjustment of assembling errors of various members is performed using various jigs ( Step S502). Accordingly, the movement of the scanning device 26 in the Z-axis direction, the movement of the carriage 24 in the X-axis direction, and the movement of the work table 22 in the Y-axis direction are linearly performed at an accurate distance.
[0051]
When the adjustment of the assembly error under such a predetermined environment (step 502) is completed, the work table 22 is then moved in the Y-axis direction under the same predetermined environment, that is, in an environment having a temperature of 20 ° C. and a humidity of 50%. It moves by a reference driving distance in a predetermined direction (step S504).
[0052]
The reference driving distance is set in advance according to the size of the work table 22 as a moving member. Further, when the work table 22 is moved in the Y-axis direction by this reference driving distance, the coordinate position and the moving direction for starting the movement are also set in advance.
[0053]
In this embodiment, the reference driving distance is set to 200 mm, and the work table 22 is moved by 200 mm from the foremost position (see FIGS. 3A and 3B) in the Y-axis direction toward the rear side. The following explanation will be given.
[0054]
Then, when the work table 22 is moved in a predetermined direction in the Y-axis direction by the reference drive distance, the number of steps engraved by the motor 36 is associated with the reference drive distance and written in the ROM 104 as reference pulse number data.
[0055]
That is, the motor 36 is rotated clockwise (in the direction of arrow a shown in FIG. 3A) in accordance with the control pulse signal. As a result, the pulley 32-1 rotates in the counterclockwise direction (the direction of the arrow b shown in the drawing), and the work table 22 disposed on the drive belt 30 moves from the frontmost position in the Y-axis direction to the rear side. Move linearly towards.
[0056]
At this time, the CPU 102 moves the work table 22 linearly by 200 mm (reference driving distance) from the front side to the rear side in the Y-axis direction. The number of steps engraved by rotating by a predetermined angle stepwise in the a direction) is detected.
[0057]
Then, the number of steps detected by the CPU 102, for example, “20132 step” is associated with the reference driving distance “200 mm” and written into the ROM 104 as reference pulse number data.
[0058]
After writing the reference pulse number data in the ROM 104 in this way, the coordinate measuring apparatus 10 is shipped (step S506) and used by the user (step S508). When the user starts using the coordinate measuring apparatus 10, when the power of the coordinate measuring apparatus 10 is turned on, various initial setting processes are performed.
[0059]
Subsequent to the various initial setting processes (step S508), correction processing during use is performed. That is, the in-use correction process is a correction process that is performed when the power of the coordinate measuring apparatus 10 is turned on.
[0060]
In use correction processing, first, the work table 22 is moved in a predetermined direction in the Y-axis direction by the number of steps indicated by the reference pulse number data (step S510).
[0061]
At this time, the movement of the work table 22 in the Y-axis direction is set to the same coordinate and the same direction as the movement of the work table 22 by the reference driving distance in the shipping correction process (step S504).
[0062]
Here, the work table 22 is moved by the number of steps indicated by the reference pulse number data in the same coordinates and in the same direction as the movement of the work table 22 by the reference drive distance in the shipping correction processing (step S504). Therefore, the moving distance that the work table 22 has moved coincides with the reference driving distance.
[0063]
More specifically, it is assumed that the temperature and humidity of the environment in which the coordinate measuring apparatus 10 is arranged at the time of use correction processing are different from the predetermined environment in the shipping correction processing (step S502 and step S504). However, since the angle at which the motor 36 rotates stepwise in a predetermined direction (step angle) and the length of the drive belt 30 are not easily affected by changes in temperature, humidity, etc., the step indicated by the reference pulse number data If the work table 22 is moved by several minutes, it is considered that the work table 22 has moved by the reference drive distance, and there is no practical problem.
[0064]
In the process of step S512, the pulse output from the linear encoder 20 when the work table 22 is moved by the number of steps indicated by the reference pulse number data in a predetermined direction in the Y-axis direction in step S510. The number of signal pulses is stored in a predetermined area of the RAM 106.
[0065]
That is, when the work table 22 moves linearly in the Y-axis direction by the number of steps indicated by the reference pulse number data in the environment where the coordinate measuring apparatus 10 is currently arranged, that is, the work is moved by the reference driving distance. The number of pulses of the pulse signal output from the linear encoder 20 when the table 22 moves linearly in the Y-axis direction is detected by the CPU 102 and stored in the RAM 106.
[0066]
Then, the quotient obtained by dividing the reference driving distance indicated by the reference pulse number data by the number of pulses stored in the RAM 106 in step S512 is output from the linear encoder 20 in the environment where the coordinate measuring apparatus 10 is currently arranged. The movement distance in the Y-axis direction of the work table 22 per unit pulse signal of the pulse signal (step S514).
[0067]
Specifically, the total length of the main scale portion 20a of the linear encoder 20 under the environment at the time of correction processing at the time of shipment is expressed as L ₀ Then, when the environment in which the coordinate measuring apparatus 10 is arranged in the correction process at the time of use coincides with the environment in the correction process at the time of shipment, the total length of the main scale unit 20a is not changed. ₀ (See FIG. 3B).
[0068]
At this time, if the number of pulses of the pulse signal output from the linear encoder 20 when the work table 22 linearly moves in the Y-axis direction by the reference driving distance of 200 mm is, for example, “200 pulses”. If so, the value is stored in the RAM 106.
[0069]
Then, by the processing in step S514, the movement distance in the Y-axis direction of the work table 22 per unit pulse signal output from the linear encoder 20 is determined to be 1.00 mm (= 200 mm ÷ 200 pulses).
[0070]
However, when the user uses the coordinate measuring apparatus 10, the temperature and humidity of the environment in which the coordinate measuring apparatus 10 is installed are the predetermined environment in the shipping correction process (step S502 and step S504), that is, the temperature 20 The humidity at 50 ° C. does not necessarily match 50%.
[0071]
Since the main scale portion 20a of the linear encoder 20 disposed in the coordinate measuring apparatus 10 is made of resin, the main scale portion 20a is easily affected by temperature, humidity, and the like. The scale portion 20a may expand and contract and the entire length may change.
[0072]
For this reason, when the environment in which the coordinate measuring apparatus 10 is arranged at the time of correction processing at the time of use does not match the environment at the time of correction processing at the time of shipment, the entire length of the main scale unit 20a is extended, Full length L ₀ Longer total length L than _a (See FIG. 3 (c)), or the overall length of the main scale portion 20a is shortened and the overall length L ₀ Short overall length L compared to _b (See FIG. 3D).
[0073]
As a result, when the work table 22 moves linearly in the Y-axis direction by the reference drive distance of 200 mm, the total length L _a The number of pulses of the pulse signal output from the linear encoder 20 having the main scale portion 20a is such that the total length of the main scale portion 20a is L ₀ For example, “190 pulses” is obtained. In this case, the movement distance in the Y-axis direction of the work table 22 per unit pulse signal output from the linear encoder 20 is determined to be 1.05 mm (= 200 mm ÷ 190 pulses) by the process of step S514.
[0074]
On the other hand, total length L _b The number of pulses of the pulse signal output from the linear encoder 20 having the main scale portion 20a is such that the total length of the main scale portion 20a is L ₀ In this case, the number of pulses is larger than that of, for example, “210 pulses”. In this case, the movement distance in the Y-axis direction of the work table 22 per unit pulse signal output from the linear encoder 20 is determined to be 0.95 mm (= 200 mm ÷ 210 pulses) by the process of step S514.
[0075]
Thus, the total length L of the main scale portion 20a of the linear encoder 20 in the environment at the time of the shipping correction process due to changes in the temperature and humidity of the environment in which the coordinate measuring apparatus 10 is installed. ₀ Is changed by the reference driving distance in step S510, the number of pulses of the pulse signal output from the linear encoder 20 at that time is stored in step S512, and in step S514. In the environment where the coordinate measuring apparatus 10 is currently arranged, the movement distance in the Y-axis direction of the work table 22 per unit pulse signal output from the linear encoder 20 is determined.
[0076]
Note that the same processing as the processing in steps S502 to S514 described above is performed by a linear encoder that outputs a pulse signal corresponding to the movement distance of the carriage 24 in the X-axis direction (not shown) and the movement of the scanning device 26 in the Z-axis direction. This is also performed in the X-axis direction and the Z-axis direction using a linear encoder that outputs a pulse signal corresponding to the distance.
[0077]
Thus, when the use correction process is completed, the process proceeds to step S516, and the coordinate measurement process of the DUT 200 is performed.
[0078]
Specifically, the motor is driven by the micro computer 100 according to a predetermined resolution, and the relative positional relationship between the scanning device 26 and the DUT 200 is XY in an XYZ orthogonal coordinate system according to the predetermined resolution. This coordinate measurement process is performed as it changes for each predetermined measurement point on the coordinate plane.
[0079]
Then, the X coordinate of the measurement point is calculated according to the movement amount in the X axis direction, and the Y coordinate of the measurement point is calculated according to the movement amount in the Y axis direction.
[0080]
For example, the Y coordinate of the measurement point is determined by the linear movement distance in the Y-axis direction of the work table 22 per unit pulse signal determined by the processing in step S514 and the movement of the work table 22 in the Y-axis direction. Based on the pulse signal output from the encoder 20, the movement distance of the work table 22 moving in the Y-axis direction is calculated.
[0081]
Then, after calculating the X coordinate and Y coordinate as measurement points, the scanning device 26 is lowered in the Z-axis direction at the calculated X coordinate and Y coordinate, and the contact 27 is brought into contact with the measured object 200. Let As a result, the Z coordinate of the measurement point (that is, the contact point) is calculated according to the change in the voltage output from the scanning device 26.
[0082]
By performing such a coordinate measurement process for each measurement point, the coordinate measuring apparatus 10 obtains coordinate data over the entire surface 200a of the object 200 and detects the shape of the surface 200a of the object 200. be able to.
[0083]
As described above, the distance measuring device according to the present invention provided in the coordinate measuring device 10 can be used, for example, by the shipping correction process (steps S502 and S504) and the use correction process (steps S510 to S514). In the Y-axis direction, the movement distance in the Y-axis direction of the work table 22 per unit pulse signal output from the linear encoder 20 is determined based on the number of steps engraved by the motor 36, and this unit pulse signal is determined. The movement distance of the work table 22 moving in the Y-axis direction is measured using the movement distance of the winning work table 22 in the Y-axis direction. Even if it is affected, the effect can be kept to a minimum, and the accurate travel distance must be measured with high accuracy. It can be.
[0084]
Further, in the distance measuring device according to the present invention, it is not necessary to provide a temperature sensor, a humidity sensor, or the like as in the distance measuring device shown in the above-mentioned “Prior Art” section. Since the scale portion 20a is formed of resin instead of glass, it can be manufactured at low cost, and an accurate movement distance can be measured with high accuracy at low cost.
[0085]
The embodiment described above may be modified as described in the following (1) to (6).
[0086]
(1) In the above-described embodiment, the linear encoder 20 is an optical (transmission type) linear encoder. However, the present invention is not limited to this. Various encoders such as a (reflective) linear encoder and a magnetic linear encoder may be used.
[0087]
The output from the linear encoder 20 is a pulse signal. However, the present invention is not limited to this, and the electrical digital quantity output from the linear encoder 20 is represented by a sign. The output value may also be used.
[0088]
(2) In the above-described embodiment, the motor 36 is a stepping motor. However, the motor 36 is not limited to this. For example, various motors for engraving steps such as a servo motor are used. You may make it use.
[0089]
(3) In the above-described embodiment, the drive belt 30 having a glass core wire is used. However, the present invention is not limited to this, and for example, a wire, a chain, etc., temperature, humidity, etc. The drive belt 30 may be configured by a material that is not easily affected by the above.
[0090]
(4) In the above-described embodiment, the distance measuring device according to the present invention is provided in the coordinate measuring device 10, but the present invention is not limited to this, and the distance of the moving object is not limited. In various apparatuses in which measurement is performed, the distance may be measured by the distance measuring apparatus according to the present invention.
[0091]
(5) In the above-described embodiment, the correction process during use (steps S510 to S514) is performed when the power of the coordinate measuring apparatus 10 is turned on. However, the present invention is not limited to this. Of course, the use correction process may be performed by a user who uses the coordinate measuring apparatus 10.
[0092]
(6) You may make it combine the above-mentioned embodiment and the modification shown in said (1) thru | or (5) suitably.
[0093]
【The invention's effect】
Since the present invention is configured as described above, even if it is affected by the temperature and humidity in the environment in which it is placed, the influence can be kept to a minimum, and the accurate travel distance can be increased at low cost. There is an excellent effect that it can be measured with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory diagram showing an example of an embodiment of a coordinate measuring device including a distance measuring device according to the present invention.
FIG. 2 is an explanatory diagram of a schematic configuration in which a part of the view in the direction of arrow A in FIG. 1 is enlarged and a linear encoder is mainly shown.
3 (a) is a schematic configuration explanatory view showing a part of the B arrow view in FIG. 1 in an enlarged manner and centering on a work table, and FIG. 3 (b) is a diagram illustrating correction when the coordinate measuring apparatus is used. The environment in which processing is performed and the environment in correction processing at the time of shipment match, and the total length of the main scale part of the linear encoder is the total length L ₀ (C) is an explanatory view showing the case of the linear encoder main environment of the linear encoder because the environment where the coordinate measuring device is arranged during the correction process at the time of use and the environment during the correction process at the time of shipment do not match. -The overall length of the scale is L _a (> Full length L ₀ (D) is an explanatory diagram showing the case of the linear encoder of the linear encoder because the environment where the coordinate measuring apparatus is arranged during the correction process at the time of use does not match the environment during the correction process at the time of shipment. The total length of the main scale is L _b (<Full length L ₀ It is explanatory drawing which shows the case of ().
FIG. 4 is a block diagram of a control system for controlling the overall operation of the coordinate measuring apparatus including the distance measuring apparatus according to the present invention.
FIG. 5 is an explanatory diagram conceptually showing an operation flow of the coordinate measuring apparatus 10 including the distance measuring apparatus according to the present invention.
[Explanation of symbols]
10 Coordinate measuring device
12 Base member
14L, 14R Prop
16 Rear member
18-1, 18-2 rail
20 Linear encoder
20a Main scale section
20b detector
22 Work table
22L Left end
22a Top surface
22b bottom surface
22c Guide part
22d Mounting part
22e exterior
24 Carriage
26 Scanning device
27 Contact
27a Tip
30 Drive belt
32-1, 32-2 Pulley
34 Gear
36 motor
38 Motor gear
100 micro computer
102 Central control unit (CPU)
104 Read-only memory (ROM)
106 Random access memory (RAM)
106-1 Coordinate data storage unit
108 Display device
200 DUT
200a surface

Claims (2)

A motor that rotates by a predetermined angle in accordance with a predetermined signal and engraves a step;
A driving belt having a glass core wire for transmitting the driving force of the motor;
A work table moved by the driving force of the motor via the driving belt ;
Detection that includes a main scale portion made of resin in which a predetermined lattice-shaped slit is formed, a light source, a lens, and a light receiving element, and is arranged so as to sandwich the main scale portion and moves together with the work table. and a section, the optical linear encoder, wherein the work table to output an output value which the detection unit to be moved according to the movement distance of the work table and moved by the motor,
Determining means for determining a moving distance of the work table per unit output value output from the optical linear encoder based on the number of steps engraved by the motor;
On the basis of the moving distance of the work table per unit output value output from the optical linear encoder which is determined by the determining means, and an output value output from the optical linear encoder Work A distance measuring device comprising: distance measuring means for measuring a moving distance of the table . The driving force of a motor that rotates by a predetermined angle according to a predetermined signal and engraves a step is transmitted to a work table via a driving belt having a glass core wire, and the work table is predetermined by the driving force of the motor. The number of steps engraved by the motor when the work table is moved by the predetermined reference movement distance is stored in correspondence with the predetermined reference movement distance. Steps,
When the work table is moved by the motor through the drive belt by the number of steps stored in the first step, a main scale portion made of a resin in which a predetermined lattice-shaped slit is formed; A detection unit that includes a light source, a lens, and a light receiving element and that is disposed so as to sandwich the main scale unit and moves together with the work table, and the work table is moved by the motor A second step of storing an output value output from an optical linear encoder that outputs an output value corresponding to a moving distance of the work table by moving the detection unit ;
From the output value output from the optical linear encoder stored in the second step and the predetermined reference movement distance, the work table per unit output value output from the optical linear encoder determine a moving distance, a moving distance of the work table per unit output value output from the optical linear encoder that the determined, based on an output value output from the optical linear encoder And a third step of measuring a moving distance of the work table .

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