KR101674554B1 - micro pattern type laser displacement sensor device having high resolution - Google Patents

Abstract

According to an aspect of the present invention, there is provided a laser displacement sensor device including a laser displacement sensor and a signal processing device, wherein the laser displacement sensor is formed of a code having alternately a predetermined pattern and a displacement surface, A code scale for performing an operation; and an optical head for generating and receiving a laser beam, wherein the optical head is a module part excluding a code scale, the laser beam generator generating laser light; A collimating lens positioned in an upper space of the laser generator and deflecting the generated laser beam into parallel light; A projection lens positioned above the collimating lens for condensing the laser beam deflected by the collimating lens and projecting the deflected laser beam onto the code scale; And an optical receiver for receiving the laser beam reflected from the code scale, wherein the projection lens is formed such that a focal point of the output side is located in a space between the projecting lens and the code scale. Is provided.

Description

[0001] The present invention relates to a laser displacement sensor having a high resolution,

The present invention relates to a laser displacement sensor device having a high resolution capable of measuring micro displacement.

Digital position sensor devices are widely used as indispensable displacement / position sensing devices for a variety of applications, including automotive systems, electronics, medical devices, printers, cameras, motion sensing systems, and robotic money pools for biosensors.

As a digital position measuring device for measuring a displacement of a specific object, a displacement measuring device using a laser is widely studied.

The laser displacement laser displacement measurement device measures the displacement of the object by using the incident information of the light reflected from the object and incident on the receiving sensor.

15 is a view for explaining a structure of a conventional laser measuring apparatus.

15, the laser light generated by the laser light source 310 is deflected into collimated light by the collimator lens 312 and irradiated to the object 320 via the focusing lens 314 for focusing.

 The laser beam having passed through the focusing condenser lens 314 is incident on the object 320 and is reflected. The laser light reflected by the object 320 is received by a receiving sensor 320 mounted on a path through which the laser light is reflected.

Thus, the laser received by the receiving sensor 320 measures the displacement using the difference between the received light amount and the reference light amount.

Such a laser displacement measuring apparatus has been continuously studied for precisely measuring the displacement due to the translational motion of several 탆 unit and the fine rotation angle of the number 慮 rad.

Such a conventional displacement measuring apparatus uses a position sensitive detector (PSD) sensor, which is composed of an array of photodetectors (PD) for receiving light from a light emitting unit and measuring the position of a light receiving point, as an optical receiver, After being reflected on the object, the position information is measured according to the amount of light incident on each PD.

Such a conventional displacement measuring apparatus has a displacement limit that can be measured according to the pixel size and number of the PSD.

Most of the components, including very small optical receivers, to have the resolution equal to the period of the code scale while identifying the direction of the displacement, must be finely controlled from a dimension perspective in order to be easily mounted on the ultra-precision instrument.

In order to improve the resolution, it is necessary to reduce the period of the code scale which determines the actual resolution, and that the optical receiver itself required by the collimated beam optical system should also decrease accordingly.

Conventionally, there is a need for a special optical system for distinguishing a grating of a very small code scale, and it is difficult to arrange the light on the structure. In order to realize a high resolution through a collimated beam-based reflection type structure, a code scale lattice period reduction and a very small optical receiver are required.

However, since the size of the photodetector (PD) is reduced to the micro scale and the fabrication process and the economical burden are large due to the fabrication with high resolution, the optical scale sensor using the reduced code scale, the optical receiver, and the collimated beam It is difficult to realize a small size and high resolution.

BACKGROUND ART [0002] A background art of this field is disclosed in Korean Patent Laid-Open Publication No. 2007-0015267 [Displacement Measurement Apparatus], which is a prior art document, a displacement measurement apparatus using laser reflected light.

Korean Registered Patent Application No. 2007-0015267 [Displacement measuring device]

It is an object of the present invention to provide an ultra-small reflective type laser displacement sensor device having a high resolution using a projected beam.

It is still another object of the present invention to provide an ultra-small laser displacement sensor device having a high resolution capable of measuring a displacement of 10 mu m class.

It is still another object of the present invention to provide an ultra-small laser displacement sensor device capable of measuring displacement of 10 mu m class and having structural tolerance in a wide range.

According to an aspect of the present invention, there is provided a laser displacement sensor device including a laser displacement sensor and a signal processing device, wherein the laser displacement sensor is formed of a code having alternately a predetermined pattern and a displacement surface, A code scale for performing an operation; and an optical head for generating and receiving a laser beam, wherein the optical head is a module part excluding a code scale, the laser beam generator generating laser light; A collimating lens positioned in an upper space of the laser generator and deflecting the generated laser beam into parallel light; A projection lens positioned above the collimating lens for condensing the laser beam deflected by the collimating lens and projecting the deflected laser beam onto the code scale; And an optical receiver for receiving the laser beam reflected from the code scale, wherein the projection lens is formed such that a focal point of the output side is located in a space between the projecting lens and the code scale. Is provided.

Also, the optical receiver includes four optical detectors, and the laser beam reflected from the code scale is formed in a pattern in which the period increases during the progress from the code scale to the optical receiver, And the code interval is larger than the code period interval of the code scale.

Four laser beam signals incident on the four photodetectors each have a pseudo-sinusoidal signal pattern. Each of the four pseudo-sinusoidal signals is subjected to a comparator synthesis process to obtain two And the displacement of the code scale is measured using one of the first and second square wave signals.

Also, the direction of the displacement is measured by analyzing the read signal among the patterns of the progress of the first square wave signal and the second square wave signal.

The collimating lens has a first space defined by a groove in which a first aspherical lens for collimating a laser beam is protruded at an upper center of a rectangular hexahedron shape, And a second space formed by a groove on which a second aspherical lens for projecting and condensing a laser beam is projected, wherein the first space and the second space face each other to form a lens assembly shape As shown in FIG.

In addition, a period interval of the code scale is 10 m, and one width of the photodetector PD is 40 m.

In addition, the optical head is 10.3 (W) x 8.33 (L ) x 6.55 (H) is formed into a size of ³ mm, the lens assembly is the height of 5.4mm and being formed with a horizontal width of 8.0mm.

Further, the laser displacement sensor device is characterized by having an angular resolution of 0.04 degrees of position resolution of 10 mu m.

Also, the laser displacement sensor device has a position resolution of 2.5 μm and an angular resolution of 0.01 ° when the phases of the first square wave signal and the second square wave signal are maintained at 90 °.

Also, the periodic interval is increased in a scattering direction along the propagation direction at a rate of 18 占 퐉 / mm.

The laser displacement sensor device is characterized in that the periodic interval of the laser beam incident on the optical receiver has a measurement allowable range in a range of 105 to 320 mu m.

Further, the laser displacement sensor device has a positional resolution of 10 mu m, and the code scale, the laser generator, the collimating lens, the projection lens, And an allowable structural tolerance of +/- 100 mu m for the alignment of the photodetector.

The laser displacement sensor device according to an embodiment of the present invention has a position resolution of 10 mu m, an angular resolution of 0.04 degrees, and can detect the rotational direction of the displacement.

The laser displacement sensor device according to an embodiment of the present invention can be designed to be flexible in the size of the optical receiver since the pattern period of the beam reflected by the projection of the laser beam can be adaptively adjusted according to the size of the optical receiver It can be very widely used.

Optical head of the laser displacement sensor manufactured in accordance with one embodiment of the present invention can be manufactured with 10.3 (W) x 8.33 (L ) of the very small size of 6.55 x (H) mm ^3.

According to an embodiment of the present invention, when the phase difference between the outputs Sig-A and Sig-B of the 4-channel PD is maintained at 90 degrees, a quadrature decoder IC is used to measure the position resolution of 2.5 mm or a high resolution .

In addition, the laser displacement sensor device according to an embodiment of the present invention has a sufficiently large structural tolerance of +/- 100 mu m as a whole against a position error that can be generated in the process of injection and assembly of components.

1 is a view for explaining the structure of a laser displacement sensor device according to an embodiment of the present invention.
2 illustrates a process of converting an output signal from a laser beam signal input to an optical receiver in a signal processing apparatus according to an embodiment of the present invention.
3 is a view for explaining the specifications and the operation principle of the laser displacement sensor fabricated according to an embodiment of the present invention.
4 shows a pattern beam profile for the traveling distance of a reflected laser beam according to an embodiment of the present invention.
FIG. 5 shows a variation of the beam pattern period according to the propagation distance of the beam.
6 illustrates an example of an assembling process of an optical head according to an embodiment of the present invention.
FIG. 7 shows an image of the laser displacement sensor 100 manufactured according to an embodiment of the present invention.
8 and 9 show output signals obtained by measuring a displacement operation in a laser displacement sensor apparatus according to an embodiment of the present invention.
FIG. 10 shows the trajectory of the laser beam and the change of the incidence period according to the alignment error of the code scale in the vertical direction.
11 shows the relationship between the incident period (Λ _B ) of the reflected laser beam incident on the optical receiver and the phase of the two output signals in the laser displacement sensor device 1 according to an embodiment of the present invention.
12 illustrates the relationship between the horizontal alignment error and the pattern period of the laser generator and the collimating lens according to an embodiment of the present invention.
13 shows the relationship between the horizontal misalignment of the projecting lens and the code scale and the incidence period according to an embodiment of the present invention.
Figure 14 shows the output waveforms of different pattern incidence periods.
15 is a view for explaining a structure of a conventional laser measuring apparatus.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities.

It is also to be understood that the terms first, second, etc. used hereinafter are merely reference numerals for distinguishing between identical or corresponding components, and the same or corresponding components are defined by terms such as first, second, no.

It is to be understood that the specific embodiments are not intended to limit the invention to the specific embodiments, but are to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured.

In the following description, the same reference numerals are used for similar parts throughout the specification.

1 is a view for explaining a structure of an optical displacement sensor device according to an embodiment of the present invention.

A laser displacement sensor device 1 according to an embodiment of the present invention includes a laser displacement sensor 10 and a signal processing device 20. [

1, the laser displacement sensor 10 includes a laser generator 11 for generating a laser beam and a collimator 11 for deflecting the laser beam generated in the laser generator 11 into parallel light and entering the projection lens 13, A projecting lens 13 for collecting a laser beam deflected by the mating lens 12 and the collimating lens 12 and projecting the laser beam to an object to be measured and an optical receiver 14 for receiving the laser beam reflected from the object to be measured An optical head 5 and a code scale 17 for forming a scale pattern and performing a displacement operation of the measurement object.

According to an embodiment of the present invention, the optical receiver 14 comprises four optical detectors (PD1, PD2, PD3, PD4) arranged in a line.

In one embodiment of the present invention, the laser generator 11 may employ a vertical cavity surface emitting laser (VCSEL) having a high yield.

Further, the code scale 17 is mounted on a measurement object to be measured, and a rotary code scale can be adopted.

In the code scale 17, a period LAMBDA _C is formed so that the lattice-shaped reflective surface and the non-reflective surface are arranged alternately and constantly.

Referring to FIG. 1, the laser beam generated from the laser generator 11 is collimated by a collimating lens 12, and then is projected onto a code scale 17 by a projection lens.

The collimating lens 12 collimates the laser beam to the projection lens 13 and converts the laser beam generated from the laser generator 11 into a parallel beam having a predetermined angle, (13).

The projection lens 13 has a projections function and functions to condense and refract the laser beam passing through the collimating lens 12 and to project the laser beam toward the code scale 17. [

According to an embodiment of the present invention, as shown in Fig. 1, the projecting lens 13 is characterized in that the focus of the aspheric lens on the output side is formed so as to be positioned between the projecting lens and the code scale 17. [

The projection laser beam E projected by the projection lens 13 is selectively reflected by a grating formed by the period Λ _C of the code scale 17 and reflected by the reflected laser beam O ) Period of the pattern is constantly increased and spatially modulated and is incident on the optical receiver 14.

Joining cycle of the beam incident to the optical receiver (Λ _B) is a reflected laser beam as the period of the laser beam pattern incident on the light receiver 14 is reflected from the code scale 11 has a projection beam projection on code scale 17 The incident angle is reflected at a small angle of reflection due to the difference in the angle of incidence due to the width of the reflection surface on which the light E is reflected and the other portion having a large angle of incidence is reflected at a larger angle of reflection than the one side.

As a result, the reflected laser beam 6 propagates in the form of a pattern gradually increasing in proportion to the distance reflected by the angle of the width of both sides of the pattern cycle of the reflected laser beam.

The reflected laser beam is collected and analyzed using an optical receiver 14 which is ultimately composed of four optical detectors PD1 to PD4 arranged in a line.

1, the reflected laser beam (O) is initially started in a pattern having the same period (Λ = Λ _{C o)} to the period of the code scale (Λ _C). Then, the period of the pattern increases linearly with the propagation distance of the reflected beam, and extends along the z 'axis which is the propagation direction of the beam.

That is, the projected beam that reaches the code scale is a beam having the same pattern as the pattern of the code scale due to the periodic lattice of the surface of the code scale 17 in which the reflective and non- And the period increases at a constant rate according to the projection angle characteristic of the projected beam and the width of the reflecting surface.

1, the optical receiver 14 cycle enters the cycle of the incoming reflected laser beam (O) at the position (Λ _B) la, and monotonically increasing between code scale 17 and the light receiver 14 The pattern period of the reflected beam is formed in the form of Λ _C <Λo <Λ _B according to the traveling distance.

According to an embodiment of the present invention, the optical receiver 14 includes four optical detectors (PDs), and each width of each of the four optical detectors PD is extended, It is designed to be responsible for a quarter of the period (Λ _B).

Optical receivers because (Λ _B) joining the cycle of an exemplary beam which is reflected the laser displacement sensor unit (1) proposed in accordance with the example is that the laser beam is the projection of the present invention can be adjusted adaptively according to the size of the optical receiver So that it can be widely used.

2 illustrates a process of converting an output signal from a laser beam signal input to an optical receiver in a signal processing apparatus according to an embodiment of the present invention.

 The reflected laser beam reflected from the code scale 14 has a certain pattern and is incident on the photodetector PD of the optical receiver 14 having a period of 4-channel photodetector PD, The final output signals Sig-A and Sig-B of the laser displacement sensor device 1 are outputted through the circuit 20.

From Fig. 2, the operation of the laser displacement sensor device can be described with reference to the sensor signal that is changed in association with it.

The optical power input to each photodetector PD included in the optical receiver 14 is determined such that the photodetector (PD) signals corresponding to PS1 to PS4 having a periodic signal correspond to the maximum and Thereby generating a vibration signal between the minimum level.

A sinusoidal shaped signal according to two adjacent photodetectors PD has a phase difference of 90 degrees.

Referring to FIG. 2, the signal processing circuit 20 includes a first comparator circuit 21 and a second comparator circuit 22.

A PS1 signal generated in the PD1 and a PS3 signal generated in the PD3 are generated through the first comparator circuit 21 to generate the square wave output signal Sig-A.

In addition, the signal processing circuit 20 generates the square wave output signal Sig-B through the second comparator circuit on the PS2 signal generated in the PD2 and the PS4 signal generated in the PD4.

That is, FIG. 2, the reference time (displacement = 0), and receives a signal for each one-quarter of the incident period (Λ _B), each optical detector (PD1 PD4 ~) at the position identified in each state, the signal processing The circuit 20 outputs two signals of the square-wave-shaped output signals Sig-A and Sig-B having a phase difference of 90 degrees. That is, as shown in Fig. 2, Sig-A and Sig-B form a pair of orthogonal signals with a phase relationship of 90 [deg.].

According to an embodiment of the present invention, one of the signals PS1 and PS3 input by the PD1 and PD3 at the measurement time point from the PD1 and PD3 signals at the reference point (displacement = 0) The displacement can be calculated from the sensor output.

Determining the size of the optical receiver with respect to the incident reflected laser beam is related to the angle?, The period of the code scale and the direction of displacement.

As a result, in the embodiment of the present invention, the inputted optical power waveforms from the four photodetectors PD1 to PD4 are converted into the square wave output signals Sig-A or Sig-B converted through the signal processing circuit 20, , It is possible to simply measure the magnitude of the displacement in accordance with the displacement of the period Λ _C of the code scale.

In addition, the directions of displacement can be easily measured by analyzing both Sig-A and Sig-B at the same time.

That is, it is possible to detect the displacement from the pulse of the output signal by displacement of the reference time point using one output signal of Sig-A or Sig-B, and to use the phase difference of the two output signals of Sig-A and Sig- And the direction of movement of the object can be measured, so that the direction control is possible.

According to an embodiment of the present invention, it is possible to have a high resolution of 10 mu m by four factors, and it is possible to obtain a phase difference of 90 degrees between signals of Sig-A and Sig- It can be improved by the resolution of the ship.

In addition, the optical displacement sensor device 1 according to an embodiment of the present invention has a characteristic in which the period lambda o of the reflected laser beam reflected from the code scale increases linearly with the distance traveled by the beam, The proposed sensor structure can control the beam pattern period.

Therefore, it is possible to precisely measure the displacement of 10 micro-scale while the size of the photodetector PD is formed larger than the period of 10 micro-code scale.

Therefore, the size of the photodetector is less sensitive than the code scale and the code scale.

Also, the displacement and the direction of movement of the object can be precisely detected using the output signals Sig-A and Sig-A.

3 is a view for explaining the specifications and the operation principle of the laser displacement sensor fabricated according to an embodiment of the present invention.

Referring to FIG. 3, the laser generator 111 models a single mode VCSEL having a characteristic of λ = 850 nm and a divergence angle of 30 °.

Also, the optical receiver 114 is formed of four photodetectors (PD), and each PD has a width of 40 mu m and a total width of four optical receivers is about 160 mu m.

The collimating and projecting lenses 112 and 113 are made of polycarbonate (n = 1.5680 @ 850 nm) material.

The asymmetric coefficients of the collimating lens 112 are 2.60 mm in diameter, 1.48 mm in radius, conic constant -2.66 x 10 ^-1 , 4 ^th , 6 ^{th ,} and 8 ^th are -8.28 x 10 ^-3 , -2.57 x 10 ^-3, and -1.05 x 10 ^-3 .

The projection lens 113 has a diameter of 3.40 mm and the other parameters have the same parameters as the collimating lens 112.

The code scale 170 was modeled as a rotating type having a lattice period of 10 μm and a radius of 13.5 mm.

The center position of the laser generator 111 formed at the lower portion of the collimating lens 112 is located 0.55 mm to the left in the x-axis direction and 0.63 mm in the y-axis from the center of the collimating lens 112.

Next, the focus position of the beam is determined in consideration of the distance between the collimating lens 112 and the projection lens 113 with respect to the z-axis.

The space distance between the first aspherical surface lens of the projection lens and the second aspheric surface lens of the collimating lens is 0.4 mm in the z-axis direction.

According to one embodiment of the present invention, the projecting lens 113 is formed in such a structure that the focus of the projected laser beam is 1.05 mm away from the projecting lens in the positive direction of the z-axis.

And the distance between the code scale 170 and the projecting lens 113 to form the joining period (Λ _B) as long as the total size of 160㎛ of four-channel optical detector from the z-axis position of the light detector (PD) the expected (Distance for forming the extended reflected laser beam) is set to 1.77 mm.

To detect the reflected laser beam reflected from the code scale, an optical receiver consisting of a 4-channel optical detector is formed at a distance of 4.67 mm from the VCSEL along the x-axis.

FIG. 4 illustrates a pattern profile of a reflected laser beam according to an exemplary embodiment of the present invention, and FIG. 5 illustrates a variation of a period of a reflected laser beam pattern according to a propagation distance.

Figures 4 and 5 illustrate how to set any z` axes passing through the center of the optical receiver from the code scale 170 to the reflected laser beam traveling direction to identify the projection characteristic of the reflected laser beam reflected at the code scale 170, FIG.

Referring to Figs. 4 and 5, z` = 0 mm at the position of the code scale, and the total travel distance of the reflected laser beam to the position of the PD is 8.16 mm.

Figure 4 shows the beam pattern period through beam profile simulation at any two points with a constant code scale on the z axis and a position of the PD.

Referring to Fig. 4, the beam pattern period at the position of the code scale is 10 mu m, and any two points are located at a constant interval of 2.72 mm and 5.44 mm from the code scale to the z & And 60 [mu] m and 110 [mu] m, respectively, and the incidence period is 160 [mu] m at the PD position.

Referring to FIG. 5, in the laser displacement sensor 100 according to the embodiment of the present invention, the period of the reflected laser beam linearly increases and increases along the propagation direction at a ratio of about 18 탆 / mm Able to know.

6 illustrates a process of assembling an optical head according to an embodiment of the present invention.

Referring to FIG. 6, the optical head 150 may be manufactured through a pick-and-place method.

The optical head 150 is assembled by mounting the lens assembly 115 and the laser generator 114 optical receiver 114 on the alignment guide 121 assembled to the base 120.

The base 120 may be formed of a PCB.

Alignment guide mounting holes 71 and 72, a laser generator mounting portion 73 and an optical receiver mounting portion 74 composed of a four-channel optical detector PD on a vertical line at the position of the aligned VCSEL, .

The alignment guide 121 is mounted on the alignment guide mounting holes 71 and 72 and the VCSEL 111 is mounted on the laser generator mounting portion 73 and the 4 channel optical detector is mounted on the optical receiver mounting portion 74.

The first mounting legs 85 and 86 are formed on the lower portion of the alignment guide 121 to facilitate mounting the alignment guide 121 in the alignment guide mounting holes 71 and 72.

Second lens mounting holes 81 and 82 are formed in both guides so that the lens assembly 115 can be easily mounted on the alignment guide 121. A second lens mount Legs 95 and 96 are mounted in the lens mounting holes 81 and 82, respectively.

According to one embodiment of the present invention, the lens assembly 115 is formed as an assembly of the collimating lens 112 and the projection lens 113, having a generally hexagonal-bezel shape in order to facilitate precision assembly into a very small size.

The collimating lens 112 has a first space formed by a groove in which a first aspherical lens for collimating a laser beam is protruded and formed at an upper center of a rectangular hexahedron shape.

The projection lens 113 has a second space formed at a lower center of the rectangular hexahedron shape by a groove in which a second aspherical lens for projecting and condensing the laser beam is protruded.

The lens assembly 115 is assembled such that the first space 162 formed on the collimating lens 112 and the second space 163 formed on the projection lens 113 face each other and are formed into a substantially rectangular hexagonal shape do.

FIG. 7 shows an image of the laser displacement sensor 100 manufactured according to an embodiment of the present invention.

Referring to FIG. 7, the laser displacement sensor 100 is completed by disposing a code scale on the optical head 150 according to a predetermined dimension.

Optical head of the laser displacement sensor 100 made according to one embodiment of the present invention is formed from a 10.3 (W) size of 8.33 x (L) x 6.55 (H) mm ^3.

In addition, the lens assembly 115 is formed to have a height of 5.4 mm and a width of 8.0 mm.

 According to one embodiment of the present invention, the collimating lens 112 and the projection lens 113 are made of polycarbonate, and the alignment guide 121 is made of polyimide.

The code scale 170 is formed with a lattice pattern having a period of 10 占 퐉 in which codes each having a reflective surface and a non-reflective surface alternately formed on the basis of a circle having a radius of 13.5 mm.

According to an embodiment of the present invention, the reflectance of the reflective surface at the surface of the code scale 170 is 95% or more, and the non-reflective surface is formed such that the incident light is processed to be scattered so that the reflectance is 5% or less.

8 and 9 show output signals obtained by measuring a displacement operation in a laser displacement sensor apparatus according to an embodiment of the present invention.

8 shows an oscilloscope screen of Output Sig-A and Sig-B outputted when the sensor module is fixed on the precision stage and the code scale 170 rotates clockwise through the motor.

9 shows an oscilloscope screen of signals Sig-A and Sig-B outputted from the signal processing device when the laser displacement sensor is fixed on the precision stage and the code scale 170 rotates counterclockwise through the motor.

At this time, the reference frequency of the output signal of the measured laser displacement sensor 100 is ~ 130 kHz, and the period of the signal is ~ 8 μs.

Referring to FIG. 8, when the code scale rotates clockwise, Sig-A precedes Sig-B, and the phase difference between the two signals is about 90 degrees.

9, it can be seen that, in the counterclockwise rotation, Sig-B precedes Sig-A, and the phase difference is about 90 deg. In the same manner as in Fig.

8 and 9, the displacement distance can be obtained by calculating the number of pulses of the square wave of Sig-A or Sig-B.

Referring to Figs. 8 and 9, one cycle of the output signal pulse is 10 mu m, and the direction of the code scale can be distinguished by comparing the read direction of the signals of the output signals Sig-A and Sig-B.

These results show that the proposed optical displacement sensor has ~ 10 μm positional resolution, ~ 0.04 ° angle resolution, and it can distinguish the direction of rotation of the code scale, I have.

Further, when the phase difference between the output signals Sig-A and Sig-B of the optical receiver satisfies 90 degrees, the quadrature decoder IC can be used to improve the position resolution to 2.5 m or the resolution of 0.01 deg.

10 shows the geometrical analysis of the projected laser beam according to the vertical alignment error of the code scale and the change of the incidence period (Λ _B ).

10, the code scale 170 is moved to a reference point 170-1 that is arranged or set at the third point 170-3 past the reference point 170-1 set by the alignment error that can be generated And may be aligned to the second point 170-2.

The first Ray bundle (RB _C ) formed at the reference point 170-1 and the second Ray bundle (RB _R ) formed at the second point 170-2 are formed for the three cases by the code scale alignment error, The center ray is selected by the third ray bundle RB _R formed at the three point 170-3 to form a locus directed toward the center of the optical receiver.

The pattern period of the reflected laser beam is determined by the incident angle to the code scale, and the angle of incidence from the normal vector to the code scale based on the first Ray bundle (RB _C ) The incident angle of the second ray bundle RB _R is relatively large compared with that of the first ray bundle and the incident angle of the third ray bundle RB _L is larger than that of the first ray bundle RB _R , The pattern period is formed to be small.

Here, the first ray bundle RB _C denotes a locus of the reference point 170-1 which is moved to the center of the optical receiver 114 by the same locus as the reference design.

10, when the position of the code scale 170 is erroneously aligned upward by + DELTA Z to be located at the third point 170-3, the reflected laser beam is moved to the first Ray bundle (RB _C ) The third Ray bundle (RB _L ) is selected to provide the displacement information.

Further, when the position of the code scale 170 is error-aligned downward by -Z so as to be located at the second point 170-2, the reflected laser beam is transmitted to the second Ray bundle (RB _C ) instead of the second Ray bundle (RB _C ) RB _R ) is selected to provide the displacement information.

Since the first to third ray bundles have propagation characteristics having different incident angles to the code scale, the incident period of the reflected laser beam measured at the optical receiver 114 side is determined according to the alignment position of the code scale 170 Appear differently.

The design incidence period Λ _B0 incident on the four optical decoders PD1 to PD4 from the first Ray bundle RB _C to the optical receiver 114 according to the embodiment of the present invention is 160 탆 to be.

Referring to FIG. 10, the period Λ _B2 of the second ray bundle (RB _R ) formed as the code scale 170 does not reach the reference point 170-1 and the incidence angle of the code scale 170 increases, Claim 3 Ray bundle _B2 of the period Λ (RB _L) is larger than Λ _B0, scale code past the aligned position the reference points (170-1) of 170 is formed wave-period reference Lt; RTI ID = 0.0 &gt; _B0 . &Lt; / RTI &gt;

Alignment errors of other hardware configurations are also affected by the orientation in a similar manner in the period of the laser beam incident on the optical receiver.

Specifically, the period of the incident reflected laser beam which is incident on the light receiver (Λ _B), when the collimating lens VCSSEL and leaves the design reference point in a horizontal + x and -x axis, is increased, the lens projecting the + z Direction, as shown in FIG.

Since the laser beam is mediated by the code scale according to the misalignment of the components of the laser beam, the incidence period of the incident reflected laser beam is reduced according to the misalignment occurring in the opposite direction.

According to the geometrical positions of the components, the performance of the proposed laser displacement sensor device 1 according to an embodiment of the present invention is consequently reduced in terms of the phase relationship between Sig-A, Sig-B and its orthogonal signals get affected.

According to an embodiment of the present invention, the laser displacement sensor device 1 can identify the direction of displacement and at the same time provide resolution capable of recognizing the period of the code scale. The periodic range of the projected laser beam pattern can be determined based on the conditions capable of generating an appropriate square wave signal pair.

A laser displacement sensor device 1 according to an embodiment of the present invention having a resolution of 10 mu m and a phase difference between two output signals according to an embodiment of the present invention can detect a pattern of a reflected laser beam by using a projection beam characteristic, (PD) of the receiver, and it is possible to detect a displacement of 10 μm by one output of the laser displacement sensor. By using the phase difference of the two output signals as the two outputs, You can see the direction of movement.

In the case of the conventional reflection type laser displacement sensor, if the alignment of the main components in the horizontal and vertical directions including the laser generator, the collimator lens, the projection lens, and the scale pattern of the measurement object is shifted, .

It is desirable to ensure tolerance to misalignment that may occur during the process and assembly of the structure in order for the microsensor to operate stably.

In one embodiment of the present invention, it is designed to have a structural tolerance capable of providing accurate measurement values for a certain range of misalignment in order to precisely measure 10 .mu.m class and to increase the measurement reliability of such a micrograph measuring instrument.

In the experimental example according to the embodiment of the present invention, even if a positional error occurs during the injection and assembly process, the manufactured laser displacement sensor device 1 detects a displacement of 10 탆 while forming a stable projection beam, tolerance to alignment error of determining the range of the incident period (Λ _B) that separates the anti-clockwise direction is provided.

In the laser displacement sensor device 1 according to the embodiment of the present invention, the reference beam pattern period in the photodetector PD reflected from the code scale is 160 m, which is the size of the 4-channel photodetector, and the output signals Sig- The reference phase difference of B is 90 degrees.

Considering the tolerance to the error of the phase difference? Between the two output signals Sig-A and B at the optical detector PD position of the optical receiver is the rotation direction of the code scale, that is, the allowable range for detecting the movement of the object.

From the viewpoint of accurately recognizing the identification of the direction of the displacement in the laser displacement sensor device 1 according to an embodiment of the present invention, it is possible if the angle is in the range of 45 DEG to 135 DEG. That is, +/- 45 ° relative to the reference Φ = 90 ° can be determined as an acceptable range for accurate measurements.

This range can be determined differently depending on the case.

11 shows the relationship between the incident period (Λ _B ) of the reflected laser beam incident on the optical receiver and the phase of the two output signals in the laser displacement sensor device 1 according to an embodiment of the present invention.

If the same design and production criteria in the laser displacement sensor unit (1) according to one embodiment of the invention Λ _B = ? _B0 = 160 占 퐉, and each of the four-channel optical detectors (PD) occupies one-quarter of the incident beam period. Therefore, the phase by a single photodetector tends to drop and rise, with increasing and decreasing in the period.

Actually, since ¼ times of Λ _B is 90 ° for one period, the phase difference between output signals Sig-A and Sig-B is Φ corresponding to 40 μm, which is the interval between the photodetectors from 360 °. Therefore, as Λ _B increases, Φ decreases according to the pattern period allocated to one optical detector.

That is, the phase relationship can be estimated that the period is changed from Φ = 135 ° to 45 ° according to the variation of the interval of 105 to 320 μm.

Therefore, the laser displacement sensor device 1 according to an embodiment of the present invention has a tolerance range that satisfies 90 degrees of reference ± 45 degrees in the range of 105 to 320 mu m.

When Λ _B is 105 μm, the optical detector of two channels takes one cycle, and the phase difference of the output signal becomes 135 °, and Λ _B becomes 45 ° at 320 μm.

The propagation characteristics of the projection beam, especially the pattern period, can be mainly influenced by the orientation of the constituent elements constituting the laser displacement sensor.

In one embodiment of the present invention, the horizontal misalignment of the laser generator (VCCSEL) and the collimating lens and the pattern period ( _B ) relationship are simulated.

FIG. 12 illustrates horizontal misalignment and incidence period? _B of a laser generator (VCCSEL) and a collimating lens according to an embodiment of the present invention.

The horizontal misalignment of the laser generator (VCCSEL) and the collimating lens is mainly related to the projection point based on the code scale.

12, when the VCSEL is misaligned along the + x direction in the range of -100 to +100 μm, the incident period Λ _B of the reflected laser beam pattern incident on the optical receiver is changed from 128 μm to 208 μm (201).

Similarly, when the collimating lens is misaligned along the x-axis direction at -100 to +100 占 퐉, the incident period? _B of the reflected laser beam pattern changes from 208 占 퐉 to 124 占 퐉.

Above results in a half cycle incident laser beam pattern according to the laser generator (VCCSEL) and -100 ~ + 100㎛ horizontal misalignment position of the collimating lens from (Λ _B) is changed as 124 ~ 208㎛ This cycle incident described earlier (Λ _B (105 to 320 占 퐉).

That is, the laser generator (VCCSEL), which is a component of the laser displacement sensor device 1 according to an embodiment of the present invention, and the alignment tolerance that allows a range of ± 100 μm with respect to the horizontal position of the collimating lens ).

Figure 13 illustrates a horizontal misalignment and the incident period (Λ _B) between the projecting lens and the scale code according to an embodiment of the present invention.

13, the time along the z-axis direction by the distance from the projecting lens to -100 ~ + 110㎛ is misaligned from the target position, the incident of the reflected laser beam pattern impinging on the optical receiver period (Λ _B ) Is changed from 132 탆 to 196 탆 (211).

Similarly, when the code scale is misaligned from the target position along the z-axis direction by a distance from -100 to +100 mu m, the incident period ( _A ) of the reflected laser beam pattern incident on the optical receiver becomes 196 mu m (212).

Therefore, when considering the maximum permissible position range (Φ = 45 ° to 135 °) of the code scale for the projecting lens and the magnification, the permissible range of the pattern period (Λ B) ± 100 μm.

12, the incidence rate of change of period (Λ _B) of the reflected laser beam pattern that is incident on the light receiver for a horizontal alignment along the x-axis change of the VCSEL and the collimating lens is approximately +0.4 ㎛ / ㎛ and -0.4 ㎛ / Mu m.

13, the projecting lens and the code rate of change of scale is incident period (Λ _B) of the reflected laser beam pattern impinging on the optical receiver for the vertical alignment changes along the z-axis is from about 0.3 ㎛ / ㎛ with each -0.36㎛ / [Mu] m.

Therefore, the laser displacement sensor device 1 according to an embodiment of the present invention has a structural tolerance up to an alignment error range of 100 mu m, and can output a pair of designed rectangular wave signals to perform a normal measurement function have.

In still another embodiment of the present invention were evaluated for the influence of reflection of the laser beam incident cycle pattern (Λ _B) according to the output of the laser displacement sensor unit (1).

(This is based on the point that the incident period (Λ _B) is sensitive to the alignment of the components.).

In Fig 14 different incident period (Λ _B), shows the power of the laser displacement sensor unit (1) to be outputted to the displacement of the scale code.

8, rectangular wave output signal pairs (Sig-A, B, C, and D) that travel in a predetermined direction with respect to an angle Φ = 72 ° 90 ° and 120 ° corresponding to incident angles Λ _B 200, Sig-B).

14, the output signal according to an embodiment of the present invention, regardless of the variation of the incidence period LAMBDA _B , can distinguish the direction of the displacement, providing a position resolution of 10 mu m equivalent to the period of the scale .

That is, even if the incidence period (Λ _B ) of the reflected laser beam pattern changes due to the position error caused by the components, the resolution direction of 10 μm and the rotation direction of the code scale can be detected.

Therefore, the laser displacement sensor device 1 according to an embodiment of the present invention has a high structural tolerance in terms of positional misalignment of its components.

According to one embodiment of the present invention, the laser displacement sensor device 1 provides an optical displacement sensor device of an integrated-passive alignment type based on an aspherical lens.

The laser displacement sensor device 1 has a characteristic that it is not sensitive to the size of a photodetector (PD) with a resolution of 10 mu m by forming a projection beam by introducing a projection lens having a focus between code scales.

In addition, in the laser displacement sensor device 1 according to the embodiment of the present invention, an optical receiver of a scale code is effectively used to convert into a pair of square wave output signals, and a code scale having a lattice structure of ~ The phase difference between the two output signals Sig-A and Sig-B can be used to detect the rotational direction and the rotational angle of about 0.04 ° with respect to the fine displacement of 10 탆.

According to an embodiment of the present invention, the positional resolution of the laser displacement sensor device 1 is 10 占 퐉, and the phase difference between the two output signals Sig-A and Sig is 90 占 to improve the position resolution to 2.5 占 퐉 .

In addition, the laser displacement sensor device 1 according to an embodiment of the present invention can detect the positional errors that may occur during the injection and assembly or operation of the components, And is easy to mass-produce.

1: Laser displacement sensor device
5, 150: Optical head
10, 100: Laser displacement sensor
11, 111: laser generator
12, 112: Collimating lens
13, 113: Projecting lens
14, 114: optical receiver
17, 170: code scale
20: signal processing device
71, 72: mounting hole
73, 74:
81, 82; Lens mounting hole
95, 96; Mounting leg
115: lens assembly
120: PCB base
121: Alignment guide

Claims (12)

A laser displacement sensor device comprising a laser displacement sensor and a signal processing device,
The laser displacement sensor comprises:
A code scale and an optical head for forming a code cycle pattern in which a reflective surface and a non-reflective surface are alternately formed and performing a displacement operation of the measurement object,
The optical head includes:
A laser generator for generating a laser beam;
A collimating lens positioned in an upper space of the laser generator and deflecting the generated laser beam into parallel light;
A projection lens positioned above the collimating lens for condensing the laser beam deflected by the collimating lens and projecting the deflected laser beam onto the code scale; And
And an optical receiver for receiving the reflected laser beam from the code scale,
Characterized in that the optical receiver comprises four optical detectors, the focus of the output side being located in a space between the projecting lens and the code scale,
Wherein the laser beam reflected from the code scale is formed in a pattern in which the period increases during the progress from the code scale to the optical receiver, and the width of the optical detector is greater than the code period of the code scale,
Wherein the collimating lens has a first space defined by a groove in which a first aspherical lens for collimating a laser beam is protruded at an upper center of a rectangular hexahedron shape, And a second space formed by a groove in which a second aspherical lens for projecting and projecting the beam is projected, and the first space and the second space are assembled so as to face each other, The laser displacement sensor device
delete The method of claim 1, wherein
Four laser beam signals incident on the four photodetectors each have a similar sinusoidal signal pattern,
Wherein each of the four quasi-sinusoidal signals is output as two first and second rectangular wave signals through a comparator synthesis process for each of two signals in the signal processing apparatus, And the displacement of the code scale is measured using the laser displacement sensor device
The method of claim 3,
And the direction of the displacement is measured by analyzing the read signal among the pattern of the progression of the first rectangular wave signal and the second rectangular wave signal.
delete The method according to claim 1,
Wherein the period of the code scale is 10 占 퐉 and the width of one of the optical detectors is 40 占 퐉. The method according to claim 1,
The optical head is 10.3 (W) x 8.33 (L ) x 6.55 (H) is formed into a size of ³ mm, the laser displacement sensor apparatus characterized in that said lens assembly is formed in a height of 5.4mm to 8.0mm in width 5. The method of claim 4,
Wherein the laser displacement sensor device has an angular resolution of 0.04 DEG with a position resolution of 10 mu m.
5. The method of claim 4,
Wherein the laser displacement sensor device has a position resolution of 2.5 占 퐉 and an angular resolution of 0.01 占 when the phases of the first rectangular wave signal and the second rectangular wave signal are maintained at 90 占
The method of claim 1,
Characterized in that the periodic interval increases in a scattering direction along the propagation direction at a rate of 18 占 퐉 / mm.
The method according to claim 6,
Wherein the laser displacement sensor device has a measurement allowable range in a range of 105 to 320 mu m at intervals of a laser beam incident on the optical receiver. The method according to claim 6,
The laser displacement sensor device has a code scale, a laser generator, a collimating lens, a projection lens, And an allowable structural tolerance of +/- 100 mu m for the alignment of the photodetector.

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